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A   COURSE 


ON 


ZOOLOGY: 


DESIGNED    FOR 


SECONDARY  EDUCATION. 


BY 

C.  DE  MONTMAHON,    AND     H.  BEAUREGARD, 

Inspector-General  of  Primary  Education,  Assistant  Naturalist  in  the  Museum 

Paris.  of  Natural  History,  Paris. 


PROFUSELY   ILLUSTRATED. 


TRANSLATED   AND   ADAPTED   FOR   AMERICAN    SCHOOLS   BY 

WM.   H.  GREENE,  M.D. 


?  St., 


PHILADELPHIA: 

J.   B.    LIPPINCOTT    COMPANY. 

1893. 


COPYRIGHT,  1892, 

BY 
J.  B.  LIPPINCOTT  COMPANY. 


EDUCATION 


PRINTED  BY  J.  B.  LIPPINCOTT  COMPANY,  PHILADELPHIA. 


:LC. 


PREFACE. 


THIS  book  forms  the  basis  of  instruction  upon  the 
natural  history  of  animals  in  the  secondary  schools  of 
France.  In  no  other  country  is  so  high  a  place  assigned 
to  the  natural  and  physical  sciences  as  a  means  of  edu- 
cation. It  therefore  follows  naturally  that  the  French 
have  the  best  text-books  upon  these  subjects.  Trans- 
lations of  their  advanced  works  have  been  the  authorized 
class-books  in  American  colleges  for  the  last  quarter 
of  a  century,  and  Paul  Bert's  "  First  Steps  in  Scientific 
Knowledge"  and  "  Primer  of  Scientific  Knowledge" 
have  made  the  successful  teaching  of  elementary  science 
possible  in  the  earlier  years  of  the  educational  course. 

The  present  work  treats  the  subject  qf  natural  history 
in  a  manner  adapted  to  <the  needs  of  secondary  schools, 
using  methods  found  by  experience  to  excite  most  in- 
terest on  the  part  of  the  pupil. 

In  the  translation  the  plan  of  the  original  work  has 
been  followed  closely ;  but  such  changes  have  been  made 
as  were  needed  to  Americanize  the  book. 

The  illustrations  form  an  important  feature  of  such  a 
work.  We  desire  to  extend  our  thanks  to  Messrs.  W. 
and  K.  Chambers  &  Co.  for  permission  to  use  cuts  from 
the  new  Chambers's  Encyclopaedia,  without  which  it 
would  have  been  extremely  difficult  to  give  the  book 
its  present  value  in  this  respect. 

Many  of  the  cuts  of  animals  are  from  photographs, 
and  of  special  scientific  value. 


CONTENTS. 


CHAPTER  PAGE 

I. — THE  ORGANIZATION  OF  MAN 7 

II. — THE  ESSENTIAL  PHENOMENA  OF  RESPIRATION  .  11 

III. — THE  ESSENTIAL  PHENOMENA  OF  CIRCULATION  18 

IV. — THE  ESSENTIAL  PHENOMENA  OF  DIGESTION  .    .  29 

V. — FUNCTIONS  OF  RELATION — NERVOUS  SYSTEM    .  48 

VI. — ORGANS  OF  SENSE 53 

VII. — FUNCTIONS  OF  LOCOMOTION— ORGANS  OF  SPEECH  68 

VIII.— THE  DOG 87 

IX.— THE  CHICKEN 94 

X. — THE  LIZARD  AND  THE  FROG 105 

XL— THE  CARP 114 

XII. — REVIEW  OF  THE  DISTINGUISHING  FEATURES  OF 

THE  FIVE  CLASSES  OF  VERTEBRATES  ....  123 

XIII. — GENERALITIES  CONCERNING  THE  ARTICULATES  .  126 

XIV.— THE  CRAYFISH 131 

XV— THE  BEETLE 138 

XVL— THE  SPIDER      146 

XVII. — WORMS— PARASITES — GENERAL  CHARACTER  OF 

ANARTHROPOD.E 154 

XVIII.  —  GENERAL  IDEAS  CONCERNING  MOLLUSKS  .    .    .  162 

XIX.— RADIATES 172 

XX. — PROTOZOA — INFUSORIA— MICROBES 180 

XXL— PRINCIPAL  ORDERS  OF  MAMMALS 188 

XXII. — CHEIROPTERA — INSECTIVORA 199 

XXIIL— CARNIVORA 204 

XXIV.— RODENTIA— EDENTATA 221 

XXV.— UNGULATA— ARTIODACTYLA 233 

XXVL— PROBOSCIDIA— PERISSODACTYLA .252 

5 


6  CONTENTS. 

CHAPTER  PAGE 

XXVII.— CETACEA  AND  SIRENIA 259 

XXVIII.— MARSUPIALS— MONOTREMES    .    .    .    264 

XXIX.— BIRDS 268 

XXX.— BIRDS  (continued)—  PASSERES :    .    .  292 

XXXI. — KEPTILES  AND  BATRACHIANS 2S9 

XXXII.— FISHES 310 

XXXIII.— INSECTS 325 

XXXIV.— SOME  USEFUL  INVERTEBRATES — PISCICULTURE  340 

XXXV. — OBNOXIOUS  INVERTEBRATES    .    .           352 


A  COURSE  ON  ZOOLOGY. 


CHAPTER  I. 
The  Organization  of  Man. 

MAN  is  an  organized  being, — that  is,  he  is  made  up  of 
distinct  parts,  each  of  which  performs  a  definite  func- 
tion. 

By  organization  is  understood  a  combination  of  parts 
or  organs,  the  word  organ  being  derived  from  the  Greek, 
and  meaning  an  instrument  or  tool. 

The  most  superficial  examination  shows  us  that  the 
organs  are  arranged  in  a  symmetrical  manner  in  the 
different  regions  of  the  body,  which  are  the  head,  the 
trunk,  and  the  limbs.  The  head  and  trunk  together 
form  the  axis  of  the  body ;  the  limbs  are  lateral  append- 


A  more  minute  examination  reveals  to  us  the  existence, 
in  each  region,  of  a  solid  framework  covered  by  the  soft- 
parts  and  the  skin,  and  protecting,  in  the  head  and  trunk, 
organs  of  great  importance  that  fill  the  interior  cavities. 

The  framework,  which  gives  its  general  form  to  the 
body,  is  called  the  skeleton.  It  is  composed  of  a  large 
number  of  pieces  differing  in  form  and  in  the  manner 
of  joining  together,  and  each  piece  is  called  a  bone.  To 
the  bones  are  attached  the  muscles  that  serve  to  move 

7 


8  A   COURSE   ON  ZOOLOGY. 

the  parts  of  the  body.  The  muscles  form  the  red  flesh  ; 
they  completely  cover  the  bones,  and,  by  their  shapes, 
their  more  or  less  pronounced  development,  and  their 
projection  from  the  general  surface,  they  give  to  the 
body  its  special  outlines. 

Three  large  cavities  and  several  smaller  ones  are  con- 
tained within  bony  structures.  First  in  order  is  the 
cranial  cavity  in  the  head,  in  which  are  contained  and 
protected  the  brain  and  its  immediate  connections;  in 
the  upper  part  of  the  trunk  is  a  large  cavity  bounded  on 
the  sides  by  the  ribs,  which  form  a  sort  of  cage  sur- 
rounding the  space  called  thorax,  breast,  or  chest,  that 
contains  the  important  organs,  the  heart  and  lungs. 
Lastly,  the  great  abdominal  cavity  occupies  the  remain- 
ing space  in  the  trunk,  and  in  this  are  placed  the  stomach, 
liver,  intestines,  kidneys,  and  bladder.  A  horizontal 
partition  separates  the  abdominal  and  thoracic  cavities. 

Besides  the  three,  large  cavities  that  we  have  men- 
tioned, there  are  several  smaller  ones,  most  of  them 
situated  in  that  part  of  the  skeleton  that  forms  the  face. 
Among  these  are  the  orbital  cavities,  or  orbits,  in  which 
are  placed  the  eyes ;  the  nasal  cavity,  for  the  organs  of 
smell ;  the  mouth,  or  buccal  cavity,  which  contains  the 
tongue  or  organ  of  taste.  It  will  be  observed  that  all 
these  cavities  of  the  face  serve  for  the  protection  of 
certain  organs  of  sense;  they  are  therefore  near  the 
cranial  cavity,  and  consequently  close  to  the  brain  and 
its  connections,  with  which,  as  we  shall  presently  see,  the 
organs  of  sense  are  directly  joined. 

We  might  also  mention  the  long,  narrow  cavity  con- 
tained within  the  whole  length  of  the  spinal  column, 
which  is  a  sort  of  sheath  enclosing  the  spinal  marrow. 

The  skeleton  not  only  protects  certain  cavities,  it  in- 


THE   ORGANIZATION    OF    MAN.  9 

eludes  certain  prolongations  or  appendages  which  serve 
as  the  framework  of  the  limbs.  These  limbs,  four  in 
number,  two  upper  and  two  lower,  are  suspended  from 
the  trunk  by  the  aid  of  what  we  may  call  bony  belts,  of 
which  the  upper  one  helps  to  form  the  shoulders,  while 
the  lower  one  forms  the  floor  of  the  abdominal  cavity, 
and  is  called  the  pelvis,  which  means  basin. 

The  various  organs  that  have  been  mentioned,  heart, 
lungs,  stomach,  intestines,  liver,  muscles,  bones,  etc.,  all 
co-operate  for  the  same  purpose, — the  maintenance  of 
life  and  the  growth  of  the  body.  But  the  parts  that  they 
take  are  very  different.  Some,  like  the  lungs,  are  speci- 
ally adapted  to  establish  between  the  blood  and  the  air 
a  contact  that  is  absolutely  necessary  for  the  life  of 
the  blood.  The  stomach,  intestines,  and  other  digestive 
organs  transform  the  food  into  substances  capable  of 
becoming  part  of  the  blood.  They  are  organs  of  nutri- 
tion or  vegetative  life.  Other  organs,  such  as  the  brain, 
the  spinal  marrow,  the  organs  of  sense,  and  the  muscles, 
help  to  establish  an  understanding  between  the  body  and 
the  outside  world :  they  are  organs  of  relation.  Gener- 
ally several  organs  assist  in  the  same  work,  and  such  are 
then  grouped  together  and  constitute  an  apparatus. 
Thus,  the  digestive  apparatus  includes  the  stomach,  the 
intestines,  the  liver,  etc.,  and  each  apparatus  can  be  sub- 
divided into  smaller  groups  of  organs,  each  of  which 
performs  a  particular  portion  of  the  work  to  be  done. 

If  this  examination  of  the  organization  is  pursued  still 
more  minutely,  the  organs  are  found  to  be  far  from  sim- 
ple :  the  various  tissues  that  constitute  the  organs  are 
composed  of  simpler  parts  or  elements,  and  these  ele- 
ments are  all  derived  from  a  fundamental  element  that 
is  called  a  cell. 


10 


A    COURSE   ON    ZOOLOGY. 


FIG.  1. 


A  cell  is  a  little  mass  having  a  varying  form,  generally 
spherical  or  ovoid,  and  made  up  of  a  jelly-like  matter 

that  is  called 
protoplasm.  In 
this  protoplasm 
is  distinguish- 
able a  parti- 
cle somewhat 
denser  than  the 
rest,  and  this  is 
the  nucleus  of 
the  cell.  It  is 
like  the  stone 
A,  cell  and  typical  nucleus:  a,  slight  membrane;  of  a  cherry  SUr- 
b,  radiating  protoplasmic  net- work ;  c,  wall  of  nu-  ,  ,  ,  , 

cleus;  d,  plasma  of  nucleus;  e,  nuclear  coil.    B,  DV  l 

nucleus  at  rest,  showing  net-work.     C,  nucleus     softer          fruity 
before  division,  showing  coiled  filament.  matter       These 

cells  are  always  so  small  that  they  cannot  be  seen  with- 
out the  aid  of  a  powerful  microscope. 

We  have  said  that  the  cell  is  the  fundamental  element 
of  all  tissues, — that  is,  the  cell  in  some  one  or  other  of 
its  modifications  produces  the  elements  which  are  grouped 
together  in  the  various  tissues. 

Sometimes  the  cell  is  elongated  like  a  slender  reed, 
this  is  a  fusiform  cell;  sometimes  it  is  star-shaped,  and 
is  said  to  be  stellate.  Or  it  may  be  thread-like,  form- 
ing a  fibre,  or  drawn  out  into  a  hollow  filament,  called 
a  tube.  All  these  elements  possess  peculiar  properties, 
and  according  to  their  forms  and  their  properties  they 
have  received  different  names.  These  names  are  also 
given  to  the  tissues  which  they  constitute.  Muscular 
tissue  is  composed  of  little  bundles  of  fibres,  which  ap- 
pear striated  under  the  microscope.  Nervous  tissue  is 


THE    ESSENTIAL    PHENOMENA    OF   RESPIRATION.  11 

made  up  by  the  union  of  various  forms  with  cylindrical 
tubes. 

We  will  finish  this  general  account  by  the  definition 
of  a  few  terms  that  merit  special  reference.  The  various 
tissues  which  form  the  glandular  organs,  such  as  the 
liver,  kidneys,  spleen,  etc.,  are  designated  as  parenchyma, 
and  the  collective  name  viscera  is  applied  to  the  different 
organs  contained  within  the  large  cavities  of  the  body. 

Membranes  are  tissues  in  the  form  of  sheets  covering 
the  surfaces  of  certain  organs.  Mucous  membranes  are 
those  which  line  the  interior  of  cavities  in  direct  connec- 
tion with  the  exterior, — the  mouth,  for  example,  is  lined 
with  the  buccal  mucous  membrane.  Serous  membranes 
line  the  interior  of  the  large  cavities  of  -the  body,  and 
are  not  in  communication  with  the  exterior ;  they  sepa- 
rate the  organs  and  facilitate  their  various  movements. 

Having  acquired  the  foregoing  general  notions,  we  will 
pass  directly  to  the  study  of  the  apparatus  of  vegetative 
life  and  those  of  the  life  of  relation.  The  first  are  those 
of  respiration,  circulation,  and  digestion.  The  second 
are  those  of  movement  (skeleton  and  muscles)  and  of 
sensation  (nervous  organs  and  organs  of  sense). 


CHAPTER  II. 
The  Essential  Phenomena  of  Respiration. 

THE  atmosphere  is  composed,  to  the  extent  of  one-fifth 
its  volume,  of  a  gas  having  very  energetic  properties, — it 
is  called  oxygen ;  the  other  four-fifths  are  another  gas, 
nitrogen,  which  may  be  considered  as  taking  no  part  in 
the  phenomena  which  are  now  to  occupy  our  attention. 


12  A   COURSE   ON   ZOOLOGY. 

All  living  beings  require  oxygen  for  the  accomplishment 
of  the  various  phenomena  of  which  their  organizations 
form  the  theatre  ;  they  derive  this  gas",  which  is  absolutely 
necessary  for  their  existence,  directly  or  indirectly  from 
the  atmosphere.  Animals  and  terrestrial  vegetables 
are  in  direct  contact  with  the  air;  aquatic  animals 
and  vegetables  support  themselves  by  the  air  held  dis- 
solved in  water.  This  dissolved  air  represents  ordina- 
rily only  one-eighth  the  volume  of  water,  but  it  contains 
a  proportion  of  oxygen  very  much  greater  than  that 
found  in  the  atmosphere ;  hence  there  is  a  sort  of  com- 
pensation. 

If  for  our  study  we  select  an  animal  breathing  the 
atmosphere  by  the  aid  of  lungs,  there  is  found  a  very 
marked  difference  between  the  composition  of  the  air 
which  enters  the  respiratory  organs  and  that  which  is 
expelled  from  the  same  organs.  In  the  last  case  but 
sixteen  or  sixteen"  and  a  half  per  cent,  of  oxygen  are 
found,  instead  of  the  twenty  per  cent,  present  in  the 
former ;  on  the  other  hand,  carbonic  acid  gas,  which  is 
found  in  an  almost  negligible  proportion  in  the  atmos- 
phere, represents  at  least  four  per  cent,  of  the  air  that 
leaves  the  lungs ;  in  addition,  vapor  of  water  is  present 
in  as  large  a  proportion  as  the  relatively  high  tempera- 
ture of  the  exhaled  air  will  permit,  while  the  atmosphere 
rarely  contains  a  quantity  bordering  on  saturation.  Dis- 
appearance oftpart  of  the  oxygen,  and  notable  increase 
in  the  proportions  of  carbonic  acid  gas  and  water 
vapor,  are,  then,  the  phenomena  which  seem  to  result 
from  the  passage  of  air  through  the  respiratory  organs. 

These  phenomena  are  exactly  the  same  as  those  pro- 
duced by  all  ordinary  combustion,  and  it  is  not  surprising 
that  at  a  very  early  date  the  two  orders  of  phenomena 


THE    ESSENTIAL    PHENOMENA    OF    RESPIRATION. 


13 


were  found  similar.  Combustion  is,  indeed,  the  ulti- 
mate object  of  the  respiratory  function.  Oxygen  is  the 
agent  necessary  for  this  combustion ;  carbonic  acid  gas 
and  water  vapor  are  the  products  resulting  from  the 
combination  of  oxygen  with  the  carbon  and  hydrogen 
which  enter  into  the  composition  of  our  tissues  and  the 
fluids  of  our  bodies.  A  candle,  lamp,  or  gas  flame  that 
burns  in  the  air  yields  exactly  the  same  products. 
FIG.  2. 


LUNGS  AND  HEART  OP  MAN.— The  left  lung  lias  been  dissected  so  as  to  show 
the  interlacing  of  air- vessels  and  blood-vessels.  P,  right  lung ;  C«,  upper 
vena  cava ;  A,  aorta ;  Vd,  right  ventricle ;  Ap,  pulmonary  artery ;  Od,  right 
auricle. 

Respiratory  Apparatus. — In  man  the  respiratory  ap- 
paratus, strictly  speaking,  is  the  lungs,  which  are  put  in 

2 


14 


A   COURSE   ON    ZOOLOGY. 


FIG.  3. 


direct  communication  with  the  external  air  by  a  large 
tube,  called  the  trachea.  The  lungs  fill  almost  the  whole 
of  the  thoracic  cavity  or  chest,  which  is,  as  we  have  seen, 
within  the  ribs,  occupying  the  upper  portion  of  the 
trunk,  and  separated  from  the  abdominal  cavity  by  a 
muscle  called  the  diaphragm. 

These  organs  are  double  and  of  unequal  size,  the  left 
lung  being  less  voluminous  than  the  right.  The  smaller 
size  of  the  left  lung  is  due  to 
the  space  occupied  by  the  heart 
in  the  left  side  of  the  thoracic 
cavity.  The  lungs  are  enveloped 
by  a  serous  membrane  called 
the  pleura,  which  separates 
them  from  each  other  and  from 
the  chest  walls. 

The  lungs  are  made  up  of  a 
large  number  of  little  vesicles, 
communicating  together  by  a 
ramifying  system  of  canals. 
In  each  lung  these  canals  join  to 
form  a  single  tube,  called  bron- 
chus, and  the  union  of  the  two 
bronchi  forms  the  trachea.  The 
trachea  rises  along  the  front  of  the  neck,  and  opens  in 
the  back  of  the  mouth  in  front  of  the  oesophagus.  It  is 
surrounded  by  a  series  of  cartilaginous  rings,  the  upper 
of  which  form  the  larynx  or  organ  of  voice,  and  produce 
exteriorly  the  little  projection  commonly  called  Adam's 
apple.  A  mucous  membrane,  which  is  a  continuation  of 
the  buccal  mucous  membrane,  covers  the  internal  walls 
of  the  trachea  and  bronchi. 

Through  the  trachea,  the  bronchi,  and  their  ramifica- 


DlAGRAM     OP    TWO     PRIMARY 

LOBULES  OF  THE  LUNGS,  mag- 
nified.—1,  bronchiole;  2,  a 
pair  of  primary  lobules  con- 
nected by  fibro-connective 
tissue;  3,  intercellular  air- 
passages;  4,  air-cells;  5, 
branches  of  the  pulmonary 
artery  and  vein. 


THE   ESSENTIAL   PHENOMENA   OF   RESPIRATION. 


15 


FIG.  4. 


BRONCHIAL 
E8 


tions  the  air  penetrates  to  the  farthest  vesicles  of  the 
lungs.  The  walls  of  these  vesicles  are  lined  with  innu- 
merable little  vessels,  some  of  which  bring  in  the  blood 
which  has  traversed  the  body  (venous  blood),  while  others 
carry  out  the  blood  which  here  in  the  lungs  becomes 
charged  with  oxygen  (arterial  blood).  The  first  are  the 
last  ramifications  of  the  pulmonary  artery ;  the  second 
unite  to  form  vessels  more 
and  more  voluminous  until, 
on  leaving  the  lungs,  they 
constitute  the  pulmonary 
vein. 

Now  that  we  know  the 
structure  of  the  pulmonary 
apparatus,  it  will  be  easy  to 
understand  how  respiration 
takes  place.  It  must  never 
be  forgotten,  however,  that 
respiration,  properly  speak- 
ing, does  not  take  place  in  the 
lungs.  These  organs  are 
simply  the  locality  in  which 
the  exchange  of  gases  takes 
place, — that  is,  the  exchange 
of  pure  air  brought  into  the 
vesicles  for  impure  air 
charged  with  carbonic  acid 
gas,  which  is  brought  by  the 
blood  to  the  ramifications  of  the  pulmonary  artery. 

Let  us  first  study  how  the  air  gets  into  the  lungs,  and 
how  it  leaves  the  lungs  after  the  exchange  of  gases,  to 
be  again  replaced  by  pure  air. 

The  conditions  necessary  for  this  entrance  and  exit 


16  A   COURSE   ON   ZOOLOGY. 

of  air  are  provided  for  by  particular  movements  of 
inspiration  and  expiration.  Movements  of  inspiration 
are  those  by  which  air  is  drawn  into  the  lungs ;  move- 
ments of  expiration  are  those  by  which  it  is  expelled. 
The  mechanism  by  which  both  these  movements  are  pro- 


m.. 


STRUCTURE  OF  THE  CHEST.— The  left  side  of  the  chest  shows  only  the  bony 
parts ;  cv,  vertebral  column :  a,  clavicle ;  c,  c,  ribs ;  st,  sternum ;  m,  muscles 
that  raise  the  upper  ribs ;  mi,  intercostal  muscles ;  d,  the  diaphragm. 

duced  is  exceedingly  simple,  and  its  action  is  much  like 
that  of  a  bellows. 

Inspiration. — When  the  chest  expands — that  is,  when 
the  lifting  of  the  ribs  and  the  breast-bone  (sternum)  and 
the  lowering  of  the  diaphragm  increase  the  capacity 
of  the  thorax,  and,  as  a  consequence,  the  rarefaction  of 
the  gas  which  this  cavity  already  contains — equilibrium 
must  be  re-established  between  the  external  and  the 


THE    ESSENTIAL    PHENOMENA    OF   RESPIRATION.  17 

internal  air.  According  to  well-known  physical  prin- 
ciples a  quantity  of  air  then  enters  the  lungs. 

Expiration, — Soon,  however,  the  ribs  and  the  sternum 
fall ;  the  diaphragm  ceases  to  contract,  and  is  forced  up- 
ward by  the  abdominal  viscera ;  the  thorax  resumes  its 
original  volume,  and  the  compression  exerted  on  the  lungs 
forces  out  a  quantity  of  air  corresponding  to  that  which 
had  entered  just  before. 

The  alternate  movements  of  inspiration  and  expiration 
are  repeated  in  man  on  an  average  sixteen  times  a  min- 
ute. The  capacity  of  the  lungs,  when  completely  filled, 
is  about  two  and  a  half  quarts,  and  the  actual  renewal 
of  air  by  each  respiratory  movement  corresponds  to 
about  thirty  cubic  inches.  If  this  last  number  be  mul- 
tiplied by  the  number  of  movements,  it  will  be  found 
that  in  every  twenty- four  hours  there  pass  through 
the  lungs  about  three  thousand  gallons,  or  four  hun- 
dred cubic  feet.  This  volume,  of  course,  varies  ac- 
cording to  numerous  circumstances.  When  the  air  enters 
the  pulmonary  vesicles  it  is  separated  from  the  blood 
only  by  the  thickness  of  the  walls  of  the  vesicles  and 
the  capillary  vessels  which  cover  their  surfaces.  The 
walls  of  the  vesicles,  like  those  of  the  capillary  blood- 
vessels, are  so  thin  that  the  thinnest  fabrics  could  give  no 
idea  of  them,  and  the  exchange  between  the  oxygen  of 
the  air  and  the  carbonic  acid  gas  of  the  blood  takes  place 
through  an  almost  impalpable  gauze. 

These  phenomena  of  exchange  constitute  only  a  part 
of  respiration,  and,  in  fact,  the  least  important  part.  The 
most  important  phenomena  take  place  in  the  depths  of 
the  tissues  to  which  passes  the  arterial  blood  charged 
with  oxygen.  They  are  chemical  reactions.  The  oxygen 
seizes  on  the  carbon  and  combines  with  it  to  form  car- 
b  2* 


18  A    COURSE   ON   ZOOLOGY. 

bonic  acid  gas,  which,  as  we  have  seen,  is  rejected  in  ex- 
piration. It  is  the  tissues  then  that  respire,  and  for  them 
that  the  blood  passes  to  the  lungs  where  it  becomes 
charged  with  oxygen.  The  tissues  do  not  all  respire 
with  the  same  intensity ;  experiments  have  shown  that 
the  muscles  absorb  the  largest  quantity  of  oxygen,  while 
the  bones  seem  to  require  the  least. 

In  any  case,  as  has  before  been  said,  respiration  is 
really  a  combustion,  taking  place  in  the  midst  of  the 
tissues,  by  the  aid  of  oxygen  carried  by  the  blood.  It 
is  well  known  that  combustion  produces  heat,  and  it 
can  be  understood  why  respiration  is  the  principal  source 
of  animal  heat. 


CHAPTER  III. 
The  Essential  Phenomena  of  Circulation. 

Circulation  is  the  name  given  to  the  course  which  the 
blood  follows  through  the  system.  The  blood  is  a  liquid 
somewhat  heavier  than  water,  having  an  insipid  taste 
and  an  unpleasant  odor ;  its  color  varies  between  dark 
red  and  scarlet.  It  is  formed  of  two  distinct  parts, — the 
plasma,  which  is  a  colorless  liquid,  and  round  or  flattened 
globules,  most  of  which  are  red,  and  these  are  called 
corpuscles.  The  plasma  forms  eight  hundred  and  sev- 
enty-five thousandths  of  the  blood,  the  corpuscles  form 
the  other  one  hundred  and  twenty-five  thousandths. 

The  corpuscles  are  composed  almost  entirely  of  a  sub- 
stance closely  resembling  white  of  egg,  and  named,  like 
the  latter,  albumen;  their  color  is  due  to  the  presence 
of  a  few  thousandths  of  a  substance  containing  iron, 


THE   ESSENTIAL   PHENOMENA   OF   CIRCULATION. 


19 


FIG.  6. 


and  called  haemoglobin.  The  quantity  of  iron  exist- 
ing in  the  blood  of  an  adult  man  does  not  exceed  a 
drachm. 

The  plasma  contains,  for  every  eight  hundred  and 
seventy-five  parts,  seven  hundred  and  ninety  parts  of 
water  and  sixty  of  albumen,  the  remainder  being  made 
up  of  small  quantities  of  more  than  fifty  different  sub- 
stances, each  of  which  either  is 
required  to  repair  the  waste  of 
certain  organs,  or  is  the  waste 
product  eliminated  from  some 
organ. 

The  blood  has  not  the  same 
appearance  and  the  same  compo- 
sition in  all  animals.  It  has  a 
red  color  only  in  the  vertebrates 
and  in  certain  annulates  belong- 
ing to  the  group  of  worms.  In 
all  other  cases  it  is  whitish, 
bluish,  yellow,  green,  or  violet. 

The  corpuscles  of  different  ani- 
mals differ  also  in  shape,  size, 
and  relative  number.  Only  mam- 
mals have  round  corpuscles ;  in 
other  animals  the  corpuscles  are 
elliptical,  and  possess  a  nucleus 
which  very  rarely  exists  in  the 
red  corpuscles  of  mammals.  Their 
size  has  no  relation  to  that  of  the  individuals :  thus, 
in  the  horse  they  are  -g-jVo"  °^  an  mcn  ^n  diameter,  in 
the  snail  25100  inch,  and  in  man  -%£$-$  inch.  The  long 
diameter  of  the  elliptical  corpuscles  of  the  frog  is  TyVrr 
of  an  inch.  Lastly,  if  we  study  the  proportion  of  these 


RED  BLOOD-CORPUSCLES, 
highly  magnified.— 1,  cor- 
puscles seen  on  their  broad 
surface ;  2,  seen  on  their 
edge;  3,  rolls  of  corpuscles, 
indicating  the  manner  in 
which  they  are  frequently 
observed  to  arrange  them- 
selves. The  remaining 
figures  more  highly  mag- 
nified :  4,  corpuscle  seen  on 
its  broad  surface;  5,  seen 
on  its  edge ;  6,  a  series  of 
corpuscles ;  7,  a  corpuscle 
in  section,  indicating  its 
biconcave  discoidal  form. 


20  A   COURSE   ON   ZOOLOGY. 

globules  to  the  entire  quantity  of  blood,  we  find  fifteen 
per  cent,  of  corpuscles  in  the  blood  of  the  tortoise,  nine 
per  cent,  in  that  of  the  horse,  and  only  six  per  cent,  in 
that  of  the  frog. 

Besides  the  red  corpuscles  in  blood,  there  are  white 
spherical  bodies  known  as  white  corpuscles,  or  leucocytes  ; 
these  are  a  little  larger  than  the  red  corpuscles,  but  much 
fewer  in  number,  there  being  in  the  blood  of  a  healthy 
man  only  one  white  corpuscle  for  about  three  hundred 
and  fifty  red  ones. 

We  have  said  in  the  chapter  on  Respiration  that  the 
blood  charged  with  oxygen  is  called  arterial  blood ;  it  is 
scarlet  in  color.  The  blood  which  circulates  in  the  tissues, 
and  which  is  charged  with  carbonic  acid  gas,  presents, 
on  the  contrary,  a  dark-red  color,  and  is  called  venous 
blood. 

Circulatory  Apparatus. — The  organs  that  -compose  the 
circulatory  apparatus  may  be  divided  into  groups, — a 


d 

a 

DIAGRAM  OF  THE  STRUCTURE  OF  AN  ARTERY  (after  Turner). 


1.  External  coat  .......... 

2.  Middle  coat  .............     c,  muscular. 

3.  Internal  coat  ........... 


central   organ,   the  heart,   and   peripheral   organs,  the 
vessels. 

We  recognize  three  systems  of  vessels,  —  the  arterial 
system,  which  receives  the  blood  from  the  heart  and 


THE    ESSENTIAL    PHENOMENA    OF    CIRCULATION. 


21 


carries  it  to  other  organs;  the  venous  system,  which 
brings  the  blood  from  the  organs  back  to  the  heart,  and 
the  capillary  system,  which  joins  together  the  other  two, 
forming  in  fact  the  termination  of  each. 

The  arteries  start  from  the  heart;  they  are  distin- 
guishable by  the  structure  of  their  walls,  which  are  com- 

FTG.  9. 


DIAGRAMS  EXHIBITING  THE  ARRANGEMENT 
OF  THE  VALVES  OF  VEINS.— A,  vein  laid 
open,  showing  the  valves  in  pairs.  B, 
longitudinal  section  of  a  vein,  indicating 
the  mode  in  which  the  valves,  by  ap- 
position of  their  free  edges,  close  its 
calibre.  The  dilated  condition  of  the 
walls  behind  the  valves  is  also  seen. 
C,  vein  distended,  showing  how  the 
sinuses  behind  the  valves  become  di- 
lated. 


CAPILLARIES.— a,  the  ar- 
tery; b,  the  vein;  c,  the 
intervening  capilla- 
ries. 


posed  of  three  distinct  layers ;  the  external  and  internal 
layers  are  soft  and  flexible,  but  the  middle  layer  is  elastic 
and  resisting.  The  veins  run  to  the  heart ;  their  walls 
have  two  layers,  corresponding  to  the  internal  and  the 
external  coats  of  the  arteries,  but  the  middle  one  is 
missing. 


22  A   COURSE   ON   ZOOLOGY. 

The  internal  membrane  of  the  veins  is  provided  through- 
out all  their  lengths  (excepting  in  the  veins  of  the  head) 
with  innumerable  little  folds,  shaped  much  like  bird's 
nests,  and  designed  to  prevent  the  flowing  back  of  the 
blood.  These  valves  of  the  veins  do  important  work  in 
the  circulation:  they  prevent  a  backward  flow  of  the 
blood,  which  is  far  from  its  starting-point,  and,  having 
lost  a  part  of  its  initial  speed,  meets  resistance  in  rising 
towards  the  heart.  The  arteries  are  under  different  con- 
ditions, and,  with  the  exception  of  the  large  ones  that 
start  from  the  heart,  do  not  possess  valves. 

The  arteries  are  much  less  numerous  than  the  veins. 
Yery  few  of  them  are  superficial ;  they  are  generally 
situated  in  deep  places,  and  each  is  usually  accompanied 
by  two  veins  that  are  called  satellites.  The  venous  sys- 
tem, on  the  contrary,  independently  of  the  veins  associ- 
ated with  the  arteries,  includes  a  very  large  number  of 
superficial  vessels. 

The  capillary  system  may  be  easily  understood  as  the 
common  continuation  of  the  other  two  systems.  Each 
of  the  last  arterial  ramifications  ends  in  a  vessel  of  very 
small  diameter,  and  after  travelling  a  certain  distance 
this  vessel  becomes  a  prolongation  of  one  of  the  last 
venous  ramifications.  Multiply  this  example  innumer- 
ably, and  we  have  an  idea  of  the  vast  net-work  whose 
ramifications  extend  in  one  manner  or  another  to  the 
smallest  and  most  remote  particles  of  our  bodies. 

The  capillary  vessels  differ  in  their  diameters,  which 
are  often  microscopic ;  some  are  so  narrow  that  the  red 
corpuscles  of  the  blood  cannot  pass  through,  and  only 
the  plasma  circulates  in  them.  Others  allow  the  red  cor- 
puscles to  pass  through  only  when  for  any  reason  the 
vessels  are  dilated. 


THE    ESSENTIAL    PHENOMENA    OP    CIRCULATION. 


23 


The  heart  is  a  hollow  muscle.  It  is  a  muscular  mass 
containing  several  cavities.  . 

It  is  situated  in  the  thorax  between  the  two  lungs, 
and  is  inclined  from  right  to  left  and  from  back  to  front, 
so  that  its  point  strikes  against  the  sixth  rib  at  each  of 
its  movements.  It  is  held  in  position  only  by  the  large 
vessels,  and  is  thus  completely  independent  of  other 
organs.  Lastly,  like  other  important  organs,  it  is  sur- 
rounded by  a  serous  membrane,  called  the  pericardium. 


FIG.  11. 


A  FRONT  VIEW  OP  THE  HEART.— 1,  the 

right  auricle  of  the  heart;  2,  the 
left  auricle;  3,  the  right  ventricle; 
4,  the  left  ventricle;  5,  6, 1,  8,  9, 10, 
vessels  through  which  the  blood 
passes  to  and  from  the  heart. 


A  BACK  VIEW  OP  THE  HEART.— 1,  the 

right  auricle ;  2,  the  left  auricle;  3, 
the  right  ventricle;  4,  the  left  ven- 
tricle ;  5,  6,  7,  the  vessels  that  carry 
the  blood  to  and  from  the  heart ;  9, 
10, 11,  the  vessels  of  the  heart. 


The  form  of  the  heart  is  that  of  an  inverted  cone ; 
its  size  is  about  equal  to  that  of  the  fist ;  its  weight  is 
somewhat  over  eight  ounces.  Its  interior  is  divided 
vertically  into  two  compartments  that  have  no  direct 
communication;  we  might  say  that  there  is  a  right 
heart  and  a  left  heart,  having  one  wall  common  to  both. 


24 


A   COURSE   ON    ZOOLOGY. 


FIG.  12. 


Each  half  is  separated  horizontally  into  two  compart- 
ments, but  these  compart- 
ments communicate  by  an 
opening  provided  with  a 
valve.  The  upper  cavities 
are  somewhat  ear-shaped, 
and  they  have  been  named 
the  right  and  left  auricles, 
while  the  lower  chambers 
are  known  as  the  right  and 
left  ventricles. 

The  walls  of  the  auricles 
are  thin  muscles  that  are 
able  to  contract  with  great 
force,  and  for  this  reason 
the  auricles  appear  very 
small  in  a  heart  emptied  of 
blood.  The  ventricles,  on 
the  contrary,  have  very 
thick  walls  and  are  very 


SECTION  OF  THE  HUMAN  HEART  (after 
His).— A,  right  auricle;  B,  right 
ventricle ;  C,  left  ventricle ;  D,  left 
auricle;  E,  partition  between  the 
two  ventricles.  Between  the  auri- 
cles and  ventricles,  on  right  and  fleshy;  their  tissue  is  a  beau- 
left,  the  tricuspid  and  mitral  valves 
with  their  cords  and  associated 


tiful  red.  The  very  thin  but 
muscles  are  shown.  very  strong  valves  which 

separate  each  auricle  from 

the  corresponding  ventricle  are  held  on  their  borders  by 
numerous  tendinous  fibres  that  are  inserted  in  the  mus- 
cular walls  of  the  ventricles.  They  can  thus  open  in 
only  one  direction,  that  which  allows  the  blood  to  flow 
from  the  auricles  to  the  ventricles.  These  valves  are  ex- 
ceedingly important  organs  ;  on  their  regular  and  normal 
action  depends  the  accomplishment  of  a  work  in  which 
the  least  irregularity  would  imperil  the  existence  of  life. 
The  heart  is  the  starting-point  or  the  termination  of 


THE    ESSENTIAL    PHENOMENA    OF   CIRCULATION. 


25 


FIG.  13. 


the  large  trunks  of  the  arterial  and  venous  circulation ; 
the  first  opens  from  the  left  side,  the  second  opens  into  the 
right  side,  and  we  might 
say  that  the  left  heart,  is 
an  arterial  heart,  while 
the  right  is  a  venous 
heart.  If  this  be  remem- 
bered, no  mistake  can  be 
made  in  understanding 
the  course  of  the  blood 
in  the  circulation.  We 
must  also  remember  that 
the  two  hearts  are  abso- 
lutely separated  by  a  mid- 
dle partition,  and  that 
the  blood  can  never  pass 

directly  from  the  one  to  DIAGRAM  OP  HEART  HALVED  AND  LAID 
the  other,  also  that  the 
blood    in    either    auricle 
can    flow    only   into    the 
corresponding  ventricle. 

It  naturally  follows 
from  this  arrangement 
that  the  blood  contained  in  either  ventricle,  being  unable 
to  escape  into  the  auricle  on  account  of  the  valve,  and 
also  unable  to  enter  the  other  ventricle,  must  be  forced 
into  the  vessels. 

The  heart  then  acts  as  follows  : 

It  is  the  pumping  organ  of  the  circulatory  system. 
Its  contractions  communicate  to  the  blood  which  passes 
through  it  a  motion  that  is  continued  throughout  the 
whole  extent  of  the  vascular  system.  The  mechanism 
must  be  studied  at  two  distinct  intervals.  At  first  there 
B  3 


OPEN  (after  Debierre).— A,  B,  C,  D,  as  in 
Fig.  12.  a,  part  of  tricuspid  valve ;  6, 
part  of  mitral ;  c,  semilunars  at  base  of 
pulmonary  artery,  a',  a',  inferior  and 
superior  venae  cavse  entering  A ;  6',  6', 
pulmonary  arteries  proceeding  from  B ; 
c?,  c',  aorta  proceeding  from  C ;  d',  d't 
pulmonary  veins  entering  D. 


26  A   COURSE   ON   ZOOLOGY. 

is  simultaneous  contraction  of  both  auricles,  forcing  the 
blood  into  the  ventricles,  and  consequent  passive  dilata- 
tion of  the  ventricles  by  the  inflowing  liquid.  At  the 
second  interval  there  is  contraction  of  the  ventricles,  and 
forced  passage  of  the  blood  into  the  aorta  and  pulmonary 
artery,  since  the  auriculo-ventricular  valves  prevent  its 
return  into  the  auricles.  The  entrances  to  the  arteries 
are  also  provided  with  valves  which  prevent  reflux  of 
blood  into  the  ventricles  when  it  has  once  entered  the 
vessels. 

That  part  of  the  circulatory  course  included  between 
the  right  ventricle  and  the  left  auricle  is  called  the  lesser 
circulation,  because  of  its  lesser  length,  or  the  pulmo- 
nary circulation,  because  it  takes  place  in  the  lungs.  The 
pulmonary  artery,  which  takes  its  origin  from  the  right 
ventricle,  is  very  short ;  a  little  over  an  inch  from  the 
heart  it  bifurcates,  and  each  branch  passing  to  one  lung 
then  divides  into  a  great  number  of  branches,  which  be- 
come smaller  and  smaller.  The  last  little  threads  are 
distributed  over  the  surface  of  the  pulmonary  vesicles, 
and  bring  the  liquid  which  they  contain  in  almost  direct 
contact  with  the  air.  Other  capillaries  receive  the  blood, 
which  has  now  become  red  arterial  blood,  and  form  a 
new  system,  which  converges  more  and  more,  and  at 
length  is  composed  of  only  four  large  vessels,  which  are 
the  pulmonary  veins ;  these  veins  empty  into  the  left 
auricle.  It  is  well  to  observe  that  here  the  name  artery 
has  been  given  to  a  vessel  that  carries  venous  blood, 
while  vessels  that  carry  arterial  blood  are  in  this  case 
called  veins.  This  naming  is  on  account  of  the  structure 
of  the  vessels  and  not  because  of  the  character  of  the 
blood  they  carry,  and  we  must  define  arteries  and  veins, 
not  as  vessels  that  carry,  the  ones  arterial  and  the  others 


THE    ESSENTIAL    PHENOMENA    OF    CIRCULATION.  27 

FIG.  14. 


Jugular  Vein 


Humeral  Artery 
Cephalic  Vein. 


Ascending 
Vena  Cava. 


Radial  Artery 


Carotid  Artery. 

ubclavian  Artery 


Arch  of  Aorta. 
Lungs. 


Thoracic  Aorta. 
Kidney. 

mac  Artery. 


Dorsal  Artery. 


THE  CIRCULATORY  SYSTEM. 


28  A   COURSE   ON   ZOOLOGY. 

venous  blood,  but  arteries  as  vessels  carrying  blood 
from  the  heart,  while  veins  return  blood  to  the  heart, 
that  blood  being  arterial  or  venous  accordingly  as  it 
comes  from  the  lungs  or  from  the  extremities  of  the 
body. 

Greater  circulation  or  general  circulation  is  the  name 
given  to  the  second  portion  of  the  blood's  course;  its 
starting-point  is  the  aorta,  and  by  it  the  blood  is  carried 
from  the  left  ventricle  to  the  right  auricle,  traversing 
the  entire  organism.  Almost  immediately  after  leaving 
the  left  ventricle,  the  aorta  sends  out  branches  for  the 
nourishment  of  the  heart  (coronary  arteries)  and  the 
lungs  (bronchial  arteries).  It  then  rises  vertically  almost 
to  the  top  of  the  sternum  and  bends  downward  and  back- 
ward, forming  an  arch,  called  the  arch  of  the  aorta. 
From  the  arch  arise  by  two  distinct  trunks  the  left 
carotid  and  the  left  subclavian,  and  by  one  common 
trunk  the  right  carotid  and  right  subclavian. 

The  carotid  arteries  distribute  numerous  ramifications 
to  the  neck  and  head.  The  subclavian  arteries,  so  called 
because  they  pass  under  the  collar-bone,  pass  to  the  arms, 
which  they  follow  throughout  the  entire  length,  taking 
names  corresponding  to  the  different  parts  they  pass 
through.  One  of  their  branches,  the  radial  artery, 
is  generally  selected  by  preference  in  feeling  the  pulse. 

The  descending  aorta  follows  the  whole  length  of 
the  spinal  column,  distributing  in  its  course  important 
branches  to  the  thorax  and  to  the  abdomen.  These  are 
the  intercostal  arteries,  for  the  muscles  of  the  ribs ;  the 
coeliac,  for  the  stomach,  liver,  and  spleen ;  the  mesenteric, 
for  the  intestines,  etc.  A  little  below  the  kidneys  a  bifur- 
cation takes  place,  forming  the  iliac  arteries,  which  carry 
the  blood  to  the  lower  limbs. 


THE   ESSENTIAL    PHENOMENA   OF   DIGESTION.  29 

The  last  arterial  ramifications  are  of  capillary  dimen- 
sions,— that  is,  their  diameter  is  hardly  as  great  as  that 
of  a  hair :  they  penetrate  to  all  parts  of  the  organs,  and 
the  work  of  nutrition  is  accomplished  by  their  aid.  They 
terminate  in  other  vessels  which  are  not  less  delicate, 
and  these  capillary  veins  receive  the  blood  deprived  of 
its  life-sustaining  elements. 

The  veins,  like  the  arteries,  generally  take  their  names 
from  the  parts  of  the  body  they  traverse:  thus,  there  are 
jugular,  renal,  mesenteric  veins,  etc.  Unlike  the  arteries, 
they  unite  together  in  their  course,  and  at  last  form  only 
two  large  vessels, — the  superior  vena  cava  and  the  in- 
ferior vena  cava.  There  is,  however,  one  exception  :  the 
portal  vein  enters  the  liver  and  divides  up  as  the  pul- 
monary artery  does  in  the  lungs,  and  the  ramifications 
afterwards  unite  to  form  two  large  vessels,  called  the 
hepatic  veins,  just  as  the  capillaries  of  the  lungs  unite  to 
form  the  pulmonary  veins. 


CHAPTER  IV. 
The  Essential  Phenomena  of  Digestion. 

THE  general  name  aliments  is  given  to  those  substances, 
whatever  may  be  their  nature,  that  are  habitually  used 
or  are  capable  of  being  used  for  nutrition.  Digestion  is 
the  operation  by  which  these  substances  are  introduced 
into  the  organization,  either  directly  or  after  having  been 
subjected  to  certain  internal  processes,  which  may  be 
chemical  or  simply  mechanical,  having  for  their  object 
the  preparation  of  the  substances  for  absorption.  The 

3* 


30 


A   COURSE   ON   ZOOLOGY. 


FlG.   15. 


digestive  apparatus  is  the  collection  of  organs  which 
serve  as  agents  in  digestion. 

The  digestive  apparatus  is  composed  of  a  long  tube 
open  at  both  extremities,  and  a  "number  of  auxiliary 
organs,  among  which  are  the  salivary  glands,  the  liver, 
the  spleen,  and  the  pancreas,  most  of  these  organs  being 
contained  in  the  abdominal  cavity. 

The  walls  of  the  digestive  tube  are  formed  by  the 
union  of  several  layers  of  various  membranes  ;  interiorly 
a  mucous  membrane  is  a  continuation  of  the  skin :  under 
this  a  fibrous  membrane  determines  the  form  of  the 

tube  ;  next  to  this  a  mus- 
cular coat  gives  the  power 
of  contraction,  and  lastly, 
a  serous  membrane  iso- 
lates the  tube  from  other 
organs. 

The  mouth  is  a  sort  of 
vestibule  to  the  digestive 
canal;  its  exterior  open- 
ing is  surrounded  by  a  cir- 
cular muscle  that  forms 

1.  The  body  of  the  lower  jaw;  2,  ramus,    tne    lips.       On    the    edges 
or  branch  of  the  jaw,  to  which  the    of    the     lips     begins     the 

that 
This 
differs     from 


muscles  that  move  it  are  attached ;  3, 
3,  the  processes  which  unite  the  lower 
jaw  with  the  head ;  i,  the  lower  and 


mucous    membrane 
has  been  mentioned; 


lateral  incisor  teeth  of  one  side;  6,  the  ^ 

hicuspid  teeth;  c,  the  cuspids  or  eye    T 

teeth;  TO,  the  three  molar  teeth;  A,    the  skin   by   its    thinness, 

shows  the  relation  of  the  permanent 

to  the  temporary  teeth. 


its  moisture,  and  its  rosy 
color.  The  lips  retain  the 
food  during  mastication,  prevent  the  saliva  from  running 
out  the  mouth,  and  aid  in  the  production  of  sound  and 
speech. 


THE    ESSENTIAL    PHENOMENA    OF   DIGESTION. 


31 


Behind  the  lips  are  the  teeth,  planted  in  the  jaws. 
There  are  thirty-two  .teeth  in  adult  man,  but  the  child 
has  only  twenty,  and.  these  are  called  milk  teeth.  The 
first  dentition  begins  between  the  ages  of  six  and 
ten  months,  the  middle  two  incisors  of  the  lower  jaw- 
usually  appearing-  first.  A  few  weeks  later  the  corre- 
sponding teeth  of  the  upper  jaw  cut  through,  then  the 

FIG.  16. 


•p  •  w 


/JL 


f  3 


ffffl-fl'fl'I 

U  ** 


THE  ADULT  TEETH.— 1,  2,  the  cutting  teeth  (incisors) ;  3,  canine  (cuspid) ; 
4,  5,  small  grinders  (bicuspids);  6,  7,  8,  grinders  (molars);  9,  9,  neck  of 
the  tooth. 

lower  lateral  incisors,  and  afterwards  the  upper  ones. 
The  lower  canines,  afterwards  the  upper  ones,  or  eye- 
teeth,  are  cut  at  the  age  of  twelve  or  fourteen  months. 
Lastly  appear  successively  eight  molars,  four  above  and 
four  below.  The  milk  teeth  begin  to  fall  out  towards 
the  seventh  year,  and  are  replaced  by  teeth  of  the  second 
dentition.  Fig.  15  shows  the  milk  teeth  fully  developed, 
and  the  second  teeth  as  germs.  We  are  born  with  the 


32 


A  COURSE  ON  ZOOLOGY. 


FIG.  17. 


germs  of  the  teeth  of  both  dentitions  already  formed, — 
that  is,  with  fifty-two  dental  embryos  enclosed  in  the 
jaws.  When  the  second  teeth  fall  they  are  not  replaced. 
There  are  then  three  kinds  of  teeth :  incisors,  canines, 
and  molars,  and  they  are  symmetrically  arranged.  An 
adult  man  has  on  each  side  of  the 
face,  and  in  each  jaw,  two  incisors, 
one  canine,  five  molars,  which  are 
classified  as  three  true  molars  and 
two  premolars  or  bicuspids. 

The  incisors  occupy  the  front  of 
the  mouth ;  next  to  them  are  the 
canines,  and  next  to  these  the  mo- 
lars. The  last  molars  do  not  often 
appear  before  adolescence;  some- 
times they  are  much  later,  and  more 
rarely  they  are  entirely  wanting. 
They  are  commonly  called  wisdom 
teeth, 

The  teeth  are  formed  of  a  pecu- 
liar substance  called  dentine  or  ivory, 
and  that  portion  of  the  dentine 
which  projects  beyond  the  gums,  and 
which  is  called  the  crown,  is  covered 
with  a  thin  layer  of  a  hard  sub- 
stance, called  enamel.  The  root  of 
the  tooth — that  is,  the  portion  which 
is  embedded  in  the  cavities  or  alveoli  of  the  jaws — is  cov- 
ered with  a  thin  coating  of  osseous  tissue,  called  cement. 
The  roots  are  single  in  the  incisors,  canines,  and  pre- 
molars ;  double  and  often  triple  in  the  true  molars. 

The  teeth,  like  all  other  organs,  are  provided  with 
nerves  and  nourishing  vessels.    These  nerves  and  vessels 


VERTICAL  SECTION  OF  A 
MOLAR  TOOTH,  moder- 
ately magnified.  —  1 , 
enamel,  the  lines  of 
which  indicate  the  ar- 
rangement ;  2,  dentine 
or  ivory ;  3,  pulp,  con- 
taining nerves  and 
nourishing  vessels ;  4, 
root,  covered  with  ce- 
ment. 


THE    ESSENTIAL    PHENOMENA    OF    DIGESTION. 


33 


FIG 


penetrate  to  a  cavity  in  the  centre  of  the  tooth,  which  is 
filled  by  a  soft  substance  called  the  pulp. 

The  tongue  is  a  muscular  organ  attached  to  the  pos- 
terior portion  of  the  floor  of  the  mouth.  Perfectly  free 
in  front,  and  endowed  with  extreme  mobility,  it  aids 
in  the  perception  of 
tastes,  in  the  forma- 
tion of  the  voice,  and 
in  deglutition  or  swal- 
lowing. Its  surface 
is  covered  with  a  di- 
gestive mucus  that 
furnishes  useful  in- 
dications to  the  phy- 
sician. Indeed,  since 
all  parts  of  the  diges- 
tive mucus  are  in 
close  sympathy  with 
each  other,  and  ordi- 
narily participate  in 
the  same  affections, 
the  condition  of  the 
tongue  usually  indi- 
cates in  a  positive 
manner  a  corre- 
sponding condition 
of  the  stomach  and 
other  portions  of  the 
digestive  canal. 

There  are  six  salivary  glands,  symmetrically  arranged, 
three  on  each  side  of  the  face.  The  largest  are  the 
parotid  glands,  and  are  situated  in  front  of  the  ears  in 
the  thickness  of  the  cheeks ;  the  maxillary  glands  are 


VERTICAL  SECTION  OP  THE  HEAD  AND  NECK.— 
c,  cavity  of  skull;  /,  falx;  s,  spinal  canal, 
leading  from  cavity  of  skull ;  n,  right  nasal 
cavity.  Below  the  hard  and  soft  palate:  t, 
tongue;  p,  pharynx;  o,  oesophagus;  e,  epi- 
glottis ;  I,  larynx. 


34  A   COURSE   ON    ZOOLOGY. 

under  the  angle  of  the  lower  jaw  ;  the  sublingual  are 
under  the  tongue.  Special  canals  or  ducts  lead  the  saliva 
secreted  by  these  glands  into  different  parts  of  the  mouth. 
The  pharynx  is  a  sort  of  funnel  just  back  of  the  mouth. 
Into  it  open  the  nasal  chambers,  called  fossae,  from  above  ; 
the  air-passages  and  oesophagus  below,  and  on  the  sides 
narrow  canals  which  connect  with  the  middle  ear. 

The  veil  of  the  palate  forms  an  imperfect  curtain  be- 
tween the  mouth  and  the  palate,  and  its  central  prolon- 
gation, the  uvula,  is  raised  during  the  act  of  swallowing. 
Behind  the  veil  of  the  palate,  on  each  side,  are  the  tonsils, 
small  glands  that  secrete  a  somewhat  viscous  liquid. 

The  oesophagus  is  a  cylindrical  membranous  tube 
which  opens  from  the  back  of  the  pharynx,  passes  down 
behind  the  windpipe,  traverses  the  thorax,  and,  entering 
the  abdominal  cavity,  ends  in  the  stomach. 

The  stomach,  as  well  as  all  the  remaining  parts  of  the 
digestive  apparatus,  is  contained  in  the  abdomen,  a  capa- 

cious cavity  separated 
from  the  chest  by  a  flat 
muscle,  called  the  dia- 
phragm. The  stomach 
occupies  the  left  upper 
portion  of  the  abdomen, 
and  extends  towards 
the  right,  somewhat  be- 
yond the  point  com- 
monly called  the  pit  of 
the  stomach.  It  is  a 

SECTION  OP  THE  STOMACH.—  a,  ducts  of  liver;    sort  of  pocket,   shaped 


b,  pylorus;    c,  bile-duct;   d,   pancreatic    Hke  a  pear,  and  having 
duct  ;  e,  cardiac  orifice. 

a  large  and  a  smaller 
curvature  and  two  orifices.     By  its  upper  orifice,  called 


THE    ESSENTIAL   PHENOMENA   OF   DIGESTION.  35 

the  cardiac,  the  stomach  is  a  continuation  of  the  cesopha- 
gus ;  by  its  lower  orifice,  the  pylorus,  it  communicates 
with  the  small  intestine.  Its  mucous  membrane  secretes 
an  acid  liquid,  which  is  a  very  active  agent  in  digestion, 
and  is  called  the  gastric  juice. 

The  small  intestine  is  a  smooth,  thin,  and  narrow  tube, 

Fio.  20. 


Small  intestine 


POSITION  OF  THE  PRINCIPAL  ORGANS  OF  DIGESTION. 

having  an  average  length  of  five  or  six  yards,  and  form- 
ing a  large  number  of  coils,  which  occupy  a  large  portion 
of  the  abdominal  cavity.  At  close  intervals  its  mucous 
membrane  forms  folds,  called  eonnivent  valves,  whose 


36  A  COURSE  ON  ZOOLOGY. 

function  is  to  retard  the  progress  of  the  food  and  present 
a  larger  surface  for  absorption.  This  membrane  bristles 
all  over  with  a  sort  of  little  hairs  or  villi,  which  give  it 
the  appearance  of  velvet,  and  which  are  true  absorbent 
organs.  The  serous  membrane,  or  mesentery,  is  a  pro- 
longation of  the  peritoneum,  a  general  serous  membrane 
which  lines  the  abdomen.  The  mesentery  forms  loops 
which  sustain  at  various  points  the  small  as  well  as  the 
large  intestine,  thus  separating  the  folds,  and  preventing 
the  tube  from  twisting  and  becoming  tangled.  Without 
knowing  the  arrangement,  it  would  be  difficult  to  under- 
stand how  the  food  can  pass  through  a  tube  so  long  and 
so  many  times  coiled  on  itself.  It  is  also  through  the 
mesentery  that  the  nerves  and  the  various  vessels  pass 
to  or  from  the  intestines. 

Although  the  small  intestine  possesses  about  the  same 
form  and  the  same  structure  throughout  its  entire  length, 
it  has  been  arbitrarily  divided  into  three  sections,  named 
duodenum,  jejunum,  and  ileum.  The  duodenum  is  the 
portion  directly  connected  with  the  stomach,  and  into  it 
empty  two  ducts,  one  of  which  carries  the  bile,  and  the 
other  the  pancreatic  juice. 

The  large  intestine  is  much  shorter  than  the  small 
one,  but  it  is  much  greater  in  diameter ;  it  also  differs  by 
having  numerous  enlargements,  by  the  very  small  num- 
ber of  absorbent  organs,  and  by  the  absence  of  convolu- 
tions. It  is  considered  as  made  up  of  three  portions: 
first,  the  caecum,  which  is  simply  an  enlargement  into 
which  the  small  intestine  opens  ;  then  the  colon,  which 
first  passes  upward  in  a  straight  line,  bends  over  in 
front  of  the  stomach,  and  turns  down,  forming  a  letter 
S.  The  rectum  forms  the  end  of  the  large  intestine  and 
of  the  digestive  tube. 


THE   ESSENTIAL    PHENOMENA    OF   DIGESTION. 


37 


FIG.  21. 


The  spleen  is  a  thin,  flat  gland,  of  a  dull-red  color,  situ- 
ated in  the  left  upper  portion  of  the  abdomen,  and  reach- 
ing from  the  large 
curve  of  the  stomach 
to  the  ribs.  This 
organ  is  usually  con- 
sidered as  forming 
part  of  the  digestive 
apparatus  ;  but  up  to 
the  present  time  its 
functions  remain  un- 
known. 

The  liver 
sometimes  a 
as  four  and 
pounds,  and 


weighs 

much 

a   half 

is    the 

the 


vs- 


THE UNDER  SURFACE  OP  THE  STOMACH  AND 
LIVER,  WHICH  ARE  RAISED  TO  SHOW  THE 
DUODENUM  AND  PANCREAS.— St,  Stomach  J 

p,  its  pyloric  end ;  I,  liver ;  g,  gall-blad- 
der: d,  duodenum,  extending  from  the 
pyloric  end  of  the  stomach  to  the  front, 
where  the  superior  mesenteric  artery,  sm, 
crosses  the  intestines;  pa,  pancreas;  sp, 
spleen ;  a,  abdominal  aorta. 


largest    of 
cera.        It    occupies 
the     whole      of    the 
right    upper    portion 

of  the  abdomen,  and  is  divided  into  several  lobes,  sepa- 
rated by  depressions  or  furrows.  It  partly  covers  the 
stomach,  and  is  itself  protected  by  the  lower  ribs.  Its 
internal  structure  is  granular,  being  formed  of  little 
glands,  which  secrete  the  bile,  and  of  an  elaborate  vas- 
cular net- work.  For  the  bile  there  is  a  reservoir,  called 
the  gall-bladder.  The  gall  is  a  sort  of  liquid  soap  ;  the 
contents  of  the  gall-bladder  of  the  ox  are  used  to  wash 
delicate  fabrics. 

A  duct   leads  from  the  gall-bladder,  and  another  di- 
rectly from  the  liver,  and  these  unite  to  form  the  com 
mon  gall-duct,  which  empties  the  bile  into  the  small  in- 
testine, a  little  below  the  pyloric  opening.    When  for  any 

4 


38  A    COURSE    ON    ZOOLOGY. 

cause  the  bile-duct  becomes  obstructed  or  the  secretion 
of  bile  is  suspended,  the  elements  of  the  bile  are  no 
longer  removed  from  the  blood,  and  that  liquid  acquires 
a  characteristic  yellow  color,  which  is  communicated  to 
the  skin. 

The  pancreas,  which  is  analogous  to  the  salivary  glands 
in  structure,  forms  a  sort  of  tongue  lying  against  the 
vertebral  column,  and  behind  and  below  the  stomach. 
Two  ducts  carry  into  the  duodenum  the  pancreatic  juice, 
these  openings  being  close  by  that  of  the  gall-duct. 

It  will  be  well  to  review  the  reciprocal  relations  of  the 
various  organs  contained  in  the  abdominal  cavity.  (Fig. 
20.)  The  stomach  occupies  the  upper  part  to  the  left ; 
the  liver  is  to  the  right  of  the  stomach,  and  somewhat  in 
front ;  the  spleen  is  left  of  the  stomach  and  slightly  be- 
hind it ;  the  transverse  colon  in  front  of  it ;  the  pancreas 
below  it ;  the  small  intestine  directly  under  it.  The  kid- 
neys— organs  that  excrete  the  urine — are  placed,  one  on 
each  side,  in  the  lumbar  region,  and  the  bladder,  the 
common  reservoir  into  which  they  discharge,  fills  the 
front  of  the  abdomen  at  the  point  corresponding  to  the 
anterior  junction  of  the  bones  of  the  pelvis.  All  these 
organs  are  closely  pressed  together,  and  yet,  by  means 
of  the  separating  prolongations  of  the  peritoneum,  they 
are  perfectly  isolated  one  from  the  other. 

Phenomena  of  Digestion, — Some  of  the  phenomena  of 
digestion  are  purely  mechanical,  relating  to  the  division, 
trituration,  and  forcing  forward  of  the  food ;  others  are 
chemical,  and  these  include  all  the  transformations  which 
the  food  undergoes  in  its  onward  passage  in  order  to 
become  fitted  for  absorption. 

These  transformations  must  end  in  the  rendering  of 
the  food  soluble,  or,  as  in  the  case  of  fats,  its  division  into 


THE    ESSENTIAL    PHENOMENA   OF    DIGESTION.  39 

exceedingly  small  particles ;  these  conditions  are  indis- 
pensable that  absorption  may  occur. 

The  successive  operations  of  digestion  have  been  clas- 
sified as  a  certain  number  of  functions,  to  which  have 
been  given  the  names  mastication,  insalivation,  degluti- 
tion, stomachic  digestion,  and  intestinal  digestion. 

The  mouth  is  the  place  of  mastication  and  insalivation. 
By  the  first  of  these  operations  the  food  is  divided  into 
fragments  small  enough  to  pass  without  difficulty  the 
narrower  portions  of  the  digestive  tube,  and  to  become 
saturated  with  the  different  liquids  it  encounters  in  its 
course. 

During  this  operation  the  tongue  constantly  carries 
between  the  teeth  those  portions  of  food  that  require 
division,  while  the  lips  retain  such  portions  as  are  forced 
outside  the  dental  arches. 

Insalivation  is  the  name  applied  to  the  action  of  the 
saliva  on  the  food  while  in  the  mouth.  The  saliva  acts 
mechanically  in  rendering  sufficiently  liquid  such  ali- 
ments as  are  too  dry ;  it  aids  in  the  agglomeration  of  the 
triturated  particles  into  little  masses  called  boluses,  and 
helps  these  boluses  to  glide  easily  into  the  oesophagus. 
It  exerts  a  chemical  action  on  starch  and  sugar,  convert- 
ing them  into  a  sweet  substance,  called  glucose,  and 
glucose  is  the  soluble  form  in  which  such  substances  are 
absorbed. 

The  saliva  is  composed  almost  entirely  of  water,  con- 
taining two  or  three  per  cent,  of  alkaline  salts  and  two  or 
three  thousandths  of  a  peculiar  principle,  called  salivary 
diastase  or  ptyalin,  which  acts  in  the  same  manner  as  the 
diastase  of  barley  in  the  manufacture  of  malt.  The  pres- 
ence of  food  in  the  mouth  causes  the  saliva  to  flow,  and  the 
flow  is  greater  with  food  which  is  rich  in  taste  and  flavor. 


40  A   COURSE   ON   ZOOLOGY. 

Solid  substances  would  be  absolutely  tasteless  were  they 
not  moistened  and  partially  dissolved  by  the  saliva.  The 
odor  or  the  sight  of  food  will  cause  a  flow  of  saliva,  the 
expression  "  to  make  the  mouth  water"  being  universally 
understood. 

At  the  moment  of  deglutition  the  tongue  gathers  the 
food  into  a  sort  of  ball  and  carries  it  into  the  pharynx, 
whose  walls  then  contract  and  force  the  bolus  into  the 
oesophagus. 

As  has  already  been  seen,  the  pharynx  has  several 
openings  :  the  entrance  of  little  portions  of  food  into  the 
nasal  passages  would  not  have  serious  consequences ;  but 
the  smallest  particle  entering  the  respiratory  tube  at 
once  causes  a  convulsive  cough  that  continues  until  the 
foreign  body  is  expelled.  Happily  this  accident  is  rare, 
because  the  opening  of  the  air-passage  is  protected  in  a 
very  thorough  manner  by  a  membranous  trap-door,  called 
the  epiglottis,  which  closes  at  the  instant  of  swallowing. 

The  progress  of  the  food  in  the  oesophagus  is  caused 
by  the  contractions  of  the  muscular  coat ;  the  weight  of 
the  food  has  nothing  to  do  with  it.  The  alimentary  mass 
hardly  enters  the  stomach  before  the  fibres  of  the  mus- 
cular tissue  of  that  organ  take  up  the  contractions  of 
the  oesophagus,  and  begin  to  knead  the  mass,  carrying  it 
at  the  same  time  from  one  end  to  the  other.  Towards 
the  end  of  this  work  the  movements  tend  to  direct  the 
food  to  the  pyloric  opening,  but  at  the  beginning  the 
direction  is  just  the  contrary, — that  is,  towards  the  large 
curvature  and  the  cardiac  orifice. 

In  the  stomach  the  food  comes  in  contact  with  the 
gastric  juice.  This  is  a  very  acid  liquid,  secreted  by  the 
mucous  membrane  of  the  stomach,  and  owing  the  greater 
part  of  its  digestive  power  to  a  substance  whose  action  is 


THE    ESSENTIAL    PHENOMENA    OF    DIGESTION. 

in  some  respects  analogous 
to  that  of  yeast,  and  which 
is  called  pepsin. 

The  gastric  juice  acts  on 
nitrogenous  matters,  such 
as  meat,  white  of  egg, 
cheese,  the  gluten  of  bread, 
etc.  It  dissolves  them  and 
renders  them  absorbable. 

It  has  been  stated,  in  the 
description  of  the  small  in- 
testine, that  the  ducts  car- 
rying the  bile  and  the  pan- 
creatic juice  open  only  a 
short  distance  from  the 
pylorus. 

The  pancreatic  juice,  an 
alkaline  liquid,  whose  ap- 
pearance resembles  that  of 
the  saliva,  but  which  differs 
somewhat  from  the  latter 
in  composition,  acts  on  the 
starchy  or  saccharine  mat- 
ters that  have  escaped  the 
action  of  the  saliva  in  pre- 
cisely the  same  manner  as 

VIEW     OF     THE     GREAT     LYMPHATIC 

TRUNKS.— 1,  2,  thoracic  duct ;  4,  the 
right  tymphatic  duct ;  5,  lymphatics 
of  the  thigh;  6,  iliac  lymphatics; 
7,  lumbar  lymphatics ;  8,  intercos- 
tal lymphatics ;  a,  superior  cava ;  b, 
left  innominate  vein;  c,  right  in- 
nominate vein;  e,  inferior  cava; 
3,  left  subclavian  vein. 


41 


42  A   COURSE   ON    ZOOLOGY. 

the  latter ;  besides,  it  exerts  an  action  on  fatty  sub- 
stances, converting  them  into  emulsions,  mixtures  in 
which  the  fat  is  broken  up  into  microscopic  drops. 

The  action  of  the  bile  is  not  as  certainly  determined. 
It  is  probable  that  it  aids  the  pancreatic  juice  in  emul- 
sifying fats,  at  the  same  time  partially  saponifying 
them, — that  is,  converting  them  into  soluble  soaps. 

While  the  food  undergoes  the  action  of  the  bile  and 
the  pancreatic  juice,  it  is  pushed  forward  by  the  contrac- 
tions of  the  muscular  tissue, — these  contractions,  having 
been  first  started  by  the  introduction  of  the  bolus  into 
the  O3sophagus,  resulting  in  what  are  called  peristaltic 
movements, — and  continues  its  passage  through  the 
many  turnings  of  the  intestinal  tube.  Absorption  takes 
place  during  this  passage  by  the  aid  of  innumerable 
villi  which  cover  the  mucous  membrane,  and  the  liquids 
pumped  in  by  these  little  suckers  enter  vessels,  called 
lacteals  or  chyle-ducts.  These  vessels  cover  the  mesen- 
tery with  an  extensive  net-work,  and  finally  unite  to  form 
one  large  canal,  called  the  thoracic  duct,  which  passes 
upward  along  the  vertebral  column,  and  pours  into  the 
left  subclavian  vein  a  whitish,  milky  liquid,  which  is 
usually  called  chyle ;  this  owes  its  opacity  and  its  white 
color  to  the  fat  globules  it  holds  in  emulsion,  just  as 
milk  is  white  because  of  the  numerous  little  butter 
globules  suspended  in  it. 

Those  parts  of  the  food  which  have  resisted  all  diges- 
tive action  pass  on  into  the  large  intestine,  whose  length 
is  but  a  small  fraction  of  that  of  the  small  intestine,  and 
are  finally  expelled  as  refuse. 


FUNCTIONS  OF  RELATION — NERVOUS  SYSTEM. 


43 


CHAPTER   V. 
Functions  of  Relation — Nervous  System. 

THE  functions  of  relation  establish  our  intercourse 
with  the  outside  world.  They  may  be  classified  as 
functions  of  sensation  and  functions  of  locomotion. 
Their  study  is  intimately  connected  with  that  of  the 
nervous  system. 

Nervous  tissue  is  made  up  of  ramified  cells,  called 
nerve-cells,  and  little  tubes  that  contain  the  ramifica- 

Fia.  23. 


NERVE-CELLS.— A,  from  sympathetic  ganglion;  B,  from  cerebrum ;  C,  from 
spinal  cord ;  a.  p.  axis  cylinder  process. 

tions  of  the  cells.  By  their  union  nerve-cells  form  a 
tissue  called  gray  matter  on  account  of  its  color.  Nerve- 
tubes  when  united  together  form  white  matter.  The 
nerves  are  made  up  exclusively  of  these  tubes. 

In  certain  localities  the  nervous  tissue  forms  long 
cords,  in  others  it  constitutes  masses  of  varying  size  and 
form.  The  cords  are  called  nerves,  and  the  masses  are 
ganglions  or  nerve-centres, 


44  A  COURSE  ON  ZOOLOGY. 

The  various  parts  of  the  nervous  system  are  usually 
classified  in  two  groups  : 

First.  The  cerebro-spinal  system,  which  includes  the 
brain,  the  spinal  cord,  and  the  nerves  which  emanate 
from  different  points  of  the  system  and  are  distributed 
to  the  different  organs. 

Second.  The  great  sympathetic  system,  which  is  com- 
posed of  series  of  small  masses  or  ganglions  connected 
together  by  a  large  number  of  nervous  ramifications, 
one  series  being  located  on  each  side  of  the  body. 

The  Cerebro-spinal  System. — The  cerebro-spinal  system 
comprises  a  central  mass,  the  brain,  a  long,  central  ap- 
pendage, called  the  spinal  cord,  and  a  chain  of  nerves,  all 
of  which  have  their  origin  in  the  brain  or  in  the  spinal 
cord. 

The  brain  is  the  collection  of  organs  contained  within 
the  cranium  or  skull :  they  are  the  cerebrum,  the  cere- 
bellum, and  the  medulla  oblongata. 

Three  membranes  cover  the  brain :  beginning  at  the 
outside,  they  are  the  dura  mater,  which  is  thick  and 
strong ;  the  arachnoid,  so  called  because  it  resembles 
a  spider's  web  ;  and  the  pia  mater,  which  is  full  of 
vessels. 

The  cerebrum,  by  itself,  occupies  almost  the  entire 
cranial  cavity.  Its  average  weight  in  man  is  somewhat 
less  than  fifty  ounces,  while  the  cerebellum  weighs  only 
about  six  ounces,  the  medulla  oblongata  only  about  an 
ounce,  and  the  spinal  cord  an  ounce.  The  cerebrum  fills 
the  front  and  upper  portion  of  the  skull ;  a  very  deep 
fissure  in  the  middle  divides  it  into  two  hemispheres, 
each  of  which  is  divided  into  several  lobes,  and  contains 
an  interior  cavity  called  a  ventricle.  The  surface  appears 
made  up  of  hills  and  valleys  by  folds  called  cerebral  con- 


FUNCTIONS  OF  RELATION — NERVOUS  SYSTEM. 


45 


volutions.     The  nervous  matter  of  the  outside  is  gray, 
the  interior  is  white. 

The  cerebellum  is  in  the  lower  back  portion  of  the 

FIG.  24. 


cmg 


MEDIAN  LONGITUDINAL  SECTION  THROUGH  HEAD  AND  UPPER  PART  OF  NECK, 

TO  SHOW   RELATION    OF    BRAIN    TO    CRANIUM     AND    SPINAL    CORD    (Original 

drawing  from  a  preparation  in  the  Anatomy  Rooms  at  Surgeons'  Hall, 
Edinburgh). — C,  cerebrum ;  cb,  cerebellum  ;  sc,  spinal  cord  ;  spc,  spinal 
column ;  mo,  medulla  oblongata,  passing  through  foramen  magnum  into 
the  spinal  cord;  pv,  pons  Varolii ;  cp,  cerebral  peduncles,  or  crura  cerebri; 
cqa,  anterior  corpora  quadrigemina  ;  cqp,  posterior  corpora  quadrigemina ; 
pg,  pineal  gland ;  pb,  pituitary  body ;  cc,  corpus  callosum,  divided  trans- 
versely ;  /,  fornix ;  mg,  marginal  gyrus ;  gf,  gyms  fornicatus ;  cmg,  calloso- 
marginal  sulcus;  O,  occipital  lobe;  po,  parieto-occipital  fissure;  cf,  calca- 
rine  fissure ;  dm,  dura  mater,  separating  cerebrum  from  cerebellum. 

skull,  and  is  separated  from  the  cerebrum  by  a  trans- 
verse fold  of  the  dura  mater.     Instead  of  convolutions 


46  A   COURSE    ON   ZOOLOGY. 

its  surface  presents  a  large  number  of  parallel  striations, 
and  the  white  matter  of  the  interior  penetrates  into  the 

FIG.  25. 


OL 


UNDER  SURFACE,  OR  BASE,  OF  BRAIN.— FL.  TL.  and  OL,  frontal,  temporal, 
and  occipital  lobes  of  the  cerebrum ;  cb,  cb,  cerebellum,  the  medulla  ob- 
longata  lying  between  its  two  lobes.  Cranial  Nerves.— I,  olfactory  lobe  (the 
nerve  of  smell) ;  2,  optic  nerve  (nerve  of  sight) ;  3,  third  or  oculo-motor 
nerve  (motor  nerve  to  most  of  the  muscles  of  the  eye) ;  4,  fourth  or  troch- 
lear  nerve  (motor  nerve  to  the  superior  oblique  muscle  of  the  eye) ;  5,  fifth, 
trigeminus  or  trifacial,  sensory  and  motor,  the  large  root  sensory  to  the 
face  and  eyes,  etc. ;  the  small  root  (motor)  to  muscles  of  mastication :  6, 
sixth  or  abducens  nerve,  to  external  rectus  muscle  of  eye,  turns  eyeball 
outwards  ;  7,  seventh  or  facial,  motor  to  muscles  of  expression  ;  8,  eighth  or 
auditory  nerve,  sensory  for  hearing  (cochlea)  and  for  equilibration  (semi- 
circular canals) ;  9,  glosso-pharyngeal,  sensory  nerve  of  taste,  and  motor  to 
some  of  the  muscles  of  deglutition ;  10,  pneumogastric,  sensory  and  motor 
to  larynx,  lung,  heart,  and  stomach  ;  11,  spinal  accessory,  motor  to  muscles 
of  heart  (inhibitory)  and  sterno-mastoid  and  trapezius  ;  12,  hypoglossal, 
motor  to  all  the  muscles  of  the  tongue ;  c\t  first  cervical  spinal  nerve. 

gray  matter  of  the  exterior,  producing  an  appearance 
like  the  branches  of   a  tree ;  this  may  be  easily  seen 


FUNCTIONS  OP  RELATION — NERVOUS  SYSTEM.     47 

on  cutting  open  the  cerebellum  of  a  sheep,  and  was  by 
the  early  anatomists  called  the  tree  of  life.  The  cere- 
bellum has  no  interior  cavity,  but  below  it  and  in  front 
are  two  ventricles  that  communicate  with  the  ventricles 
of  the  cerebrum. 

The  medulla  oblongata  connects  both  the  cerebrum 
and  the  cerebellum  with  the  spinal  cord.  From  the  pos- 
terior base  of  the  cerebrum  and  from  the  cerebellum 
project  large  columns  that  appear  like  stems,  and  are 
called  cerebral  peduncles.  Below  is  a  thick  transverse 
band  or  bridge,  called  pons  Varolii,  and  above,  between 
the  cerebrum  and  cerebellum,  are  little  eminences,  called 
optic  thalami  or  quadrig-eminal  tubercles.  The  union  of 
the  peduncles  of  the  cerebrum  and  those  of  the  cerebel- 
lum forms  the  rachidian  bulb.  The  fibres  of  this  bulb, 
six  in  number,  four  in  front  and  two  behind,  are  direct 
continuations  of  those  of  the  spinal  cord.  The  middle 
two  in  front,  or  anterior  pyramids,  as  they  are  called, 
come  from  the  cerebrum,  and  are  crossed  in  such  a 
manner  that  those  which  arise  in  the  right  hemi- 
sphere form  the  left  pyramid,  while  those  having 
origin  in  the  left  hemisphere  constitute  the  right- 
pyramid. 

This  crossing  explains  why  paralysis  that  affects  one 
hemisphere  of  the  brain  produces  loss  of  sensibility  or 
of  movement  on  the  opposite  side. 

The  cranial  nerves,  so  called  because  they  come  directly 
from  the  brain,  inside  of  the  skull,  form  the  first  twelve 
pairs  of  the  forty -three  pairs  in  the  cerebro-spinal  sys- 
tem. Their  functions  are  very  different,  comprising  the 
special  senses,  and  the  mobility  and  sensation  of  different 
parts  of  the  face.  One  of  them,  the  pneumogastric, 
passes  down  into  the  thorax  and  abdomen,  and  plays  a 


48  A   COURSE   ON   ZOOLOGY. 

very  important  part  in  respiration,  digestion,  and  circu- 
lation. 

The  spinal  cord  is  a  direct  continuation  of  the  medulla 
oblongata,  and  is  contained  in  the  hollow  canal  of  the 
vertebral  column,  down  which  it  passes  as  far  as  the 
loins.  It  is  composed  of  gray  matter  interiorly  and 
white  matter  exteriorly,  a  structure  opposite  to  that 
of  the  brain.  The  different  bundles  of  fibres  of  which  it 
is  made  up  are  separated  by  regular  grooves,  and  have 
enlargements  at  the  points  where  the  nerves  distributed 
to  the  upper  and  lower  limbs  have  their  origin. 

The  matter  of  the  cord  is  very  delicate.  A  violent 
shock  or  a  strong  pressure  upon  it  may  occasion  imme- 
diate paralysis  or  even  death.  Such  a  condition  happens 
when  the  vertebra,  especially  those  of  the  neck,  are  dis- 
located, and  their  articular  surfaces  no  longer  exactly 
correspond. 

The  thirty-one  pairs  of  spinal  nerves — that  is,  nerves 
proceeding  from  the  spinal  cord — are  classified  as  eight 
pairs  of  cervical,  twelve  dorsal,  five  lumbar,  and  six 
sacral.  These  nerves  have  exit  from  the  spinal  column 
through  lateral  openings,  called  intervertebral  openings. 
They  have  double  roots,  anterior  and  posterior.  The 
anterior  roots  are  motor  nerve-fibres,  while  the  posterior 
are  sensory  nerves.  These  two  roots  soon  unite  to  form 
little  masses  of  nerve-cells,  called  ganglions,  and  from 
the  nerve  that  starts  from  the  ganglions  proceed  the 
branches  which  divide  up  into  smaller  and  smaller  nerves 
as  they  are  distributed  to  the  extreme  surface  of  the 
body. 

The  interlacing  of  nerve-branches  forms  what  is  called 
a  plexus.  The  first  four  pairs  of  cervical  nerves  form  the 
cervical  plexus,  supplying  the  neck ;  the  other  four  pairs 


FUNCTIONS  OF  RELATION — NERVOUS  SYSTEM.     49 

FIG.  27. 

FIG.  26. 


CEREBRO-SPINAL  SYSTEM. 
— M,  medulla  oblongata ; 
C  1  to  8,  cervical  nerves ; 
D  1  to  12,  dorsal  nerves ; 
L  1  to  5,  lumbar  nerves ; 
S  1  to  6,  sacral  nerves. 


A   BACK   VIEW  OF  THE  BRAIN  AND    SPINAL 

NERVES.— 1,  cerebrum;  2,  cerebellum; 
3,  spinal  cord ;  4,  nerves  of  the  face ;  5, 
brachial  plexus  of  nerves;  6,  7,  8,  9, 
nerves  of  the  arm;  10,  nerves  that  pass 
under  the  ribs;  11,  lumbar  plexus  of 
nerves ;  12,  sacral  plexus  of  nerves ;  13, 
14, 15, 16,  nerves  of  the  lower  limbs. 
5 


50  A  COURSE  ON  ZOOLOGY. 

form  the  brachial  plexus,  whose  branches  are  distributed 
to  the  arms.  The  dorsal  nerves  are  distributed  to  the 
trunk,  and  are  very  simple  in  their  directions,  having  no 
plexus.  The  lumbar  nerves,  on  the  contrary,  all  unite 
to  form  a  large  and  deeply-placed  plexus,  called  the 
lumbar  plexus.  Lastly,  from  the  first  pairs  of  sacral 
nerves  is  formed  the  sacral  plexus,  which  terminates  in 
a  flattened  trunk,  the  great  sciatic  nerve,  and  this  is 
both  the  thickest  and  the  longest  nerve  in  the  body.  It 
supplies  the  lower  limb,  sending  branches  to  all  parts  of 
the  leg  and  foot. 

The  principal  nerves  are  generally  named  after  the 
parts  in  which  they  are  situated.  Thus,  there  is  a  crural 
nerve,  a  brachial  nerve,  a  cubital  nerve,  etc.  By  fol- 
lowing out  in  minute  examination  the  nerves  as  they 
pass  to  the  organs,  it  may  be  seen  that  the  last  filaments 
of  motor  nerves  penetrate  into  the  muscular  tissue,  while 
those  of  the  nerves  of  general  sensation  terminate  in 
the  thickness  of  the  skin. 

Great  Sympathetic  System.— The  great  sympathetic 
system  is  composed  of  ganglions  and  nerves,  the  gan- 
glions being  nerve-centres.  The  ganglions  in  the  neck 
and  thorax  are  arranged  in  a  regular  manner  in  pairs 
along  the  spinal  column.  In  the  'other  parts  of  the 
system  they  are  scattered,  being  found  in  the  neigh- 
borhood of  all  the  organs,  or  even  in  the  organs  them- 
selves. 

The  nerves  that  make  up  this  system  form  numerous 
plexi,  the  plexi  appearing  at  frequent  intervals  and  in 
the  most  complicated  forms.  Each  organ  has  an  impor- 
tant plexus :  thus  there  is  a  cardiac  plexus,  a  mesenteric 
plexus,  a  renal  plexus,  a  hypogastric  plexus.  The  last  is 
situated,  as  its  name  indicates,  in  the  upper  part  of  the 


FUNCTIONS  OF  RELATION — NERVOUS  SYSTEM.    51 
FIG.  28. 


REPRESENTS  THE  SYMPATHETIC  GANGLIA,  AND  THEIR  CONNECTION  WITH  OTHER 
NERVES.— A,  A,  A,  the  semilunar  ganglion  and  solar  plexus,  situated  below 
the  diaphragm  and  behind  the  stomach.  This  ganglion  is  situated  in  the 
region  (pit  of  the  stomach)  where  a  blow  gives  severe  suffering.  D,  D,  D, 
the  thoracic  (chest)  ganglia,  ten  or  eleven  in  number ;  E,  E,  the  external 
and  internal  branches  of  the  thoracic  ganglia;  G,  H,  the  right  and  left 
coronary  plexus,  situated  upon  the  heart;  I,  N,  Q,  the  inferior,  middle, 
and  superior  cervical  (neck)  ganglia ;  1,  the  renal  plexus  of  nerves  that 
surrounds  the  kidneys;  2,  the  lumbar  (loin)  ganglion;  3,  their  internal 
branches;  4,  their  external  branches;  5,  the  aortic  plexus  of  nerves  that 
lies  upon  the  aorta.  The  other  letters  and  figures  represent  nerves  that  con- 
nect important  organs  and  nerves  with  the  sympathetic  ganglia. 


52  A   COURSE   ON   ZOOLOGY. 

abdomen,  and  may  be  considered  as  the  centre  of  the 
sympathetic  system.  It  has  even  been  called  the  ab- 
dominal brain. 

Functions  of  the  Nervous  System. — The  nervous  sys- 
tem is  the  seat  of  sensation,  of  intellectual  perception, 
and  of  voluntary  and  involuntary  motion ;  at  the  same 
time  it  presides  over  the  acts  of  nutrition  and  secretion, 
and  regulates  the  whole  economy. 

It  is  easy  to  prove  the  universal  influence  of  this  sys- 
tem. Whenever  nerve-action  is  arrested  the  function  of 
the  part  is  interrupted,  and  all  manifestations  of  life  are 
destroyed.  If  the  nerve  supplying  the  kidneys  be  cut, 
those  organs  immediately  cease  to  produce  their  ordinary 
excretion  ;  if  the  nerve  distributed  to  any  member  be  cut, 
the  member  at  once  loses  all  sensation,  all  possibility  of 
motion.  This  is  a  law  to  which  there  is  no  exception. 

Each  of  the  different  parts  of  the  nervous  system  has 
its  own  particular  work  to  do.  Nutrition,  sensation,  and 
movement  are  not  under  the  influence  of  the  same  nerve- 
centres. 

Nutrition  is,  to  a  great  extent,  under  the  supervision 
of  the  great  sympathetic,  and  for  this  reason  the  name 
nervous  system  of  organic  life  has  been  sometimes  applied 
to  the  sympathetic  system.  On  the  other  hand,  sensa- 
tion and  movement  are  under  the  control  of  the  cerebro- 
spinal  system.  If,  as  is  the  case,  ramifications  of  both 
systems  are  found  distributed  all  over  the  body,  it  is 
because  all  our  organs  must  live  and  be  nourished,  and 
to  a  certain  extent  all  are  endowed  with  sensation  and 
movement. 

To  understand  the  operations  of  the  nervous  system, 
it  must  be  remembered  that  the  nerves  have  no  other 
function  than  to  establish  communication  between  the 


ORGANS   OF    SENSE.  53 

nerve-centres  and  the  peripheral  organs,  and  that  they 
are  therefore  conductors  comparable  to  the  telegraph- 
wires  connecting  the  telegraphic  stations.  Those  nerves 
which  go  from  the  organs  of  sense  to  the  nerve-centres 
are  called  sensory  nerves :  they  transmit  to  the  nerve- 
centres  the  impressions  they  receive  at  the  organs  of 
sense.  The  nerves  which  go  from  the  nerve-centres  to 
the  muscles  are  motor  nerves :  their  action  excites  the 
muscles  and  therefore  produces  movements. 


CHAPTER   VI. 
Organs  of  Sense. 

Organs  of  sense  is  the  name  applied  to  the  organs 
placed  in  intimate  communication  with  the  nervous  sys- 
tem, and  having  for  their  purpose  the  establishment  of 
our  relations  with  the  outside  world, — that  is,  the  objects 
around  us.  These  objects  are  known  to  us  only  by  the 
impressions  they  produce  on  our  senses.  An  apple  is 
something  that  presents  to  our  fingers  a  certain  contour 
and  a  certain  hardness  and  feeling,  to  our  eyes  a  certain 
form  and  color,  to  our  taste  and  smell  a  peculiar  taste 
and  a  characteristic  odor.  Four  different  kinds  of  im- 
pressions— touch,  sight,  taste,  and  smell — here  combine 
to  give  us  a  definite  idea  of  an  object.  Whenever  we 
are  as  perfectly  informed  of  any  matter  as  in  this,  case, 
there  is  little  that  can  be  risked  of  the  correctness  of 
our  conclusions ;  but,  if  we  were  guided  by  the  im- 
pressions of  one  sense  alone,  that  of  sight,  for  example, 
we  would  be  easily  deceived ;  the  form  and  color  of  an 


54 


A   COURSE   ON    ZOOLOGY. 


apple  ably  painted  on  canvas  could  deceive  our  eyes  and 

make  us  believe  that  the  fruit 
was  actually  present.  If  all 
our  means  of  perception — our 
organs  of  sense — were  absent, 
the  apple  would  disappear, 
and  for  us  would  cease  to 
exist. 

In  the  physiological  exam- 
ination of  the  functions  of 
sensation  in  man,  we  must 
consider  five  distinct  appa- 
ratus, serving  as  the  instru- 
ments of  five  distinctly  char- 
acterized series.  These  are 
touch,  taste,  smell,  hearing, 
and  sight. 

Touch. — The  sense  of  touch 
notifies  us  of  the  contact  of 
other  bodies  with  our  per- 
sons ;  it  gives  us  many  no- 

VERTICAL  SECTION  OF  THE  SKIN  OF  tions  concerning  the  different 

THE  FOREFINGER  ACROSS  TWO  OF         ,  .        ,  _,.      *  , 

THE  RIDGES  OF  THE  SURFACE  physical  properties  and  con- 
(highly  magnified).-! ,  dermis,   ditions    of    bodies,    such    as 

composed  of  an  intermixture  of     „  , . 

bundles  of  fibrous  tissue ;  2,  epi-   form>  dimensions,  consistence, 

dermis;  3,  homy  layer;  4,  soft  elasticity,     weight,     tempera- 
layer;  5,  subcutaneous   connec-  T                    , 
tive  and  adipose  tissue;  6, tactile  ture>  etc-       ln   man  tne  sense 
papillae;  7, sweat-glands; 8,  duct;  of    touch    exists  more  Or  less 
9,  spiral  passage  from  the  latter  -,        -,          •,              ,,            ,  • 

through  the  epidermis;  io,  ter-   developed  over  the  entire  sur- 

mination  of  the  passage  on  the    face  of  the  skin. 

summit  of  ridge.  The  g]dn  ^  compoaed  of  t WQ 

layers,  the  epidermis  and  the  derm.     The  epidermis  is 
the  external  layer ;  it  is  formed  of  superposed  layers  of 


ORGANS    OF    SENSE.  55 

epithelial  cells,  of  which  the  deeper  are  prismatic  and 
regular.  As  they  are  nearer  the  surface,  these  cells  are 
more  and  more  flattened,  and,  instead  of  being  thick 
and  soft,  as  in  the  interior,  they  are  thin  and  horny. 
The  most  superficial  are  like  little  scales,  and  they  gradu- 
ally become  detached  and  fall  off,  but  are  at  the  same 
time  continually  replaced  by  new  layers  of  cells  pro- 
duced from  the  deeper  ones.  This  desquamation  of  the 
epidermis  takes  place  continually  and  imperceptibly  in 
man,  but  in  many  animals  it  occurs  at  the  same  time 
over  the  whole  surface,  so  that  at  certain  intervals  the 
body  seems  to  emerge  from  a  thin  covering. 

The  coloring  matter  or  pigment  is  in  the  deep  layers  of 
the  epidermis.  The  pigment  consists  of  a  large  number 
of  microscopic  granules  of  a  brown  color,  which  give  to 
the  skin  a  darker  or  lighter  shade. 

The  derm,  which  is  just  under  the  epiderm,  is  com- 
posed of  strong  fibres,  crossing  and  interlacing  in  every 
direction.  Little  conical  eminences  may  be  seen  pro- 
jecting from  the  surface  of  the  derm,  and  in  these  papil- 
lae, as  they  are  called,  are  the  terminations  of  the  nerves 
of  touch.  The  projections  of  the  papillae  are  the  cause 
of  the  regularly- arranged  series  of  elevations  that  are 
separated  by  little  furrows  on  the  surface  of  the  skin. 
Their  number  is  large  in  all  parts,  but  becomes  enormous 
in  positions  where  the  sense  of  touch  is  most  acute. 

The  sudoriferous  glands  are  contained  in  the  subcuta- 
neous cellular  tissue  ;  their  excreting  ducts  pass  through 
the  derm  and  open  obliquely  on  the  surface  of  the  epiderm 
in  the  furrows  between  the  papilla.  The  perspiration 
is  an  acid  liquid,  having  a  chemical  composition  that  is 
complicated  as  well  as  very  variable.  The  sebaceous 
glands  are  in  the  thickness  of  the  derm ;  they  are 


56 


A    COURSE   ON    ZOOLOGY. 


abundant  in  certain  parts  of  the  face,  as  on  the  fore- 
head and  on  the  sides 


FIG 


of  the  nose.  The  oily 
matter  they  secrete  lu- 
bricates the  skin,  pre- 
serving its  softness 
and  elasticity. 

The  hair  appears  in 
its  most  advanced  de- 
velopment on  the  skin 
covering  the  cranial 
bones,  but,  excepting 
on  the  palms  of  the 
hand  and  soles  of  the 
feet,  a  colorless  down, 
having  a  velvety  ap- 
pearance, may  be  ob- 
served over  the  whole 
body.  The  nails  are 
for  the  anatomist 
only  agglomerated 
hairs,  somewhat 
changed  in  form  and 
color. 

The  hairs  grow 
from  small  bulbs  or 
swellings  placed  in 
minute  cavities  in 
the  derm.  They  are 
fibrous  tubes  contain- 
ing a  semifluid  matter, 
and  in  this  is  found 
the  coloring  principle, 


14 


SECTION  OF  THE  SKIN  OP  THE  SCALP,  WITH  A 
HAIR-FOLLICLE  (highly  magnified)  (Leidy). 
— 1,  cuticle;  2,  epidermal  rete ;  3,  tactile 
papilla ;  4,  dermis ;  5,  hair  papilla ;  6,  ves- 
sel; 7,  hair-bulb;  8,  hair;  9,  inner  root- 
sheath  ;  10,  outer  root-sheath ;  11,  wall  of 
the  hair-follicle;  12,  erector  muscle;  13, 
sebaceous  follicles ;  14,  subcutaneous  are- 
olar  tissue  and  fat. 


ORGANS    OP    SENSE. 


57 


FIG.  31. 


u 


THE  MOUTH,  CUT  AND  STRETCHED  OPEN  TO  SHOW  THE  TONGUE  AND  PALATE.— 

MI,  lower  jaw ;  Li,  lower  lip ;  Ls,  upper  lip ;  i,  upper  incisors ;  c,  canine ; 
m,  premolars ;  M,  molars ;  I,  uvula ;  pp,  posterior  pillars  of  the  palate ; 
pa,  anterior  pillars ;  a,  tonsil;  pf.  fungiform  papillse;  pc,  calciform  papillae. 


58  A  COURSE  ON  ZOOLOGY. 

usually  consisting  of  various  sulphides  and  salts  of 
iron. 

Taste. — The  sense  of  taste  gives  us  notions  of  savors. 
Its  principal  organ  is  the  tongue,  whose  upper  surface  is 
covered  with  papilla?  that  are  similar  to  the  papilla?  of 
touch,  and  are  called  gustatory  papillae.  They  receive 
nerve-filaments  coining  principally  from  the  glosso- 
pharyngeal  nerve.  These  papilla?  are  shaped  like  mush- 
rooms (fungiform),  or  like  the  calyces  of  flowers  (calci- 
form),  and  the  latter  form  seems  to  be  the  kind  particu- 
larly serving  as  organs  of  taste.  The  calciform  papillae 
may  be  seen  regularly  distributed  on  the  posterior  upper 
surface  of  the  tongue,  where  their  grouping  forms  a  letter 
V,  called  the  lingual  V. 

Not  all  substances  are  tastable :  thus  a  piece  of  glass 
produces  on  the  tongue  only  an  impression  of  touch. 
In  order  that  a  substance  may  be  tasted  it  must  either 
be  liquid  or  capable  of  being  dissolved  by  the  saliva. 
This  fact  explains  why  the  taste  becomes  dulled  when 
the  mouth  and  tongue  are  dry.  The  causes  of  the 
difference  in  tastes  are  unknown.  Frequently  certain 
impressions  are  considered  as  tastes  that  depend  much 
more  directly  on  the  sense  of  smell. 

Smell. — The  sense  of  smell,  which  gives  us  notions  of 
odors,  is  located  in  the  nasal  fossa?. 

The  direct  cause  of  odorous  impressions  is  the  contact 
with  our  olfactory  organs  of  minute  particles  of  the 
odorous  substance  in  the  form  of  gas  or  vapor.  As  the 
air  we  breathe  passes  continually  over  the  parts  in  which 
the  sense  of  smell  resides,  it  is  impossible  that  an  odor 
should  exist  around  us  without  our  noticing  it  almost 
immediately. 

The  nasal  fossa?  form  a  double  cavity  above  the  roof 


ORGANS   OP   SENSE.  59 

of  the  mouth,  and  opening  behind  into  the  pharynx. 
(Fig.  32.)  Their  walls  are  bony,  as  well  as  the  median 
septum  between  them,  excepting  towards  the  nares  or 
nasal  orifices,  where  they  are  cartilaginous  and  gifted 
with  a  certain  amount  of  mobility.  Interiorly  the  nasal 
fossae  are  lined  with  a  pituitary  membrane ;  this  mem- 
brane, which  is  a  continuation  of  the  mucous  membrane 
of  the  mouth,  follows  all  the  sinuosities  of  the  nose  and 
penetrates  into  the  cavities  or  sinuses  of  the  frontal  bone 
and  of  the  superior  maxillary  bones.  In  it  is  spread  out 
the  olfactory  nerve,  whose  ramifications  collect  the  im- 
pressions left  by  odorous  particles. 

FIG.  32. 


A  SIDE-VIEW    OF    THE     PASSAGE  OF  THE  NOSTRILS    AND    THE  DISTRIBUTION   OF 

THE  OLFACTORY  NERVE. — 4,  the  olfactory  nerve ;  5,  the  fine  divisions  of 
this  nerve  on  the  membrane  of  the  nose ;  6,  a  branch  of  the  fifth  pair  of 
nerves. 

The  perception  of  odors  takes  place  almost  entirely  in 
the  upper  part  of  the  nasal  fossa3.  The  nose  proper 
seems  to  have  only  a  mechanical  function  in  the  opera- 
tion ;  it  is  a  receiver,  which  takes  in  and  arrests  the  pas- 
sage of  the  particles  of  odorous  substances.  After  acci. 


60  A    COURSE   ON    ZOOLOGY. 

dents  which  have  resulted  in  its  loss,  the  nose  may  be 
replaced  by  an  artificial  nose  without  the  olfactory  organs 
losing  their  sensibility. 

The  nasal  fossae  receive  the  lachrymal  secretion  by  a 
duct  coming  from  the  internal  angle  of  the  orbit.  This 
maintains  that  condition  of  humidity  of  the  pituitary 
membrane  necessary  for  its  perception  of  odors. 

Hearing. — The  sense  of  hearing  resides  in  the  ear  and 
enables  us  to  perceive  sounds. 

The  ear  receives  sounds  as  the  nose  receives  odors,  but 
there  is  this  difference,  that  while  odors  are  probably 
material  particles  emanating  from  odorous  bodies,  sounds 
represent  only  the  result  of  vibrations  of  a  sounding  body. 
Sonorous  vibrations  are  transmitted  more  or  less  perfectly 
according  to  the  elasticity  of  the  medium  interposed 
between  the  vibrating  body  and  the  ear.  They  proceed 
from  one  place  to  another  like  the  waves  produced  by 
a  stone  falling  in  water,  and  in  this  manner  they  pen- 
etrate the  ear,  where  they  are  received  by  the  nerve 
whose  province  is  to  transmit  the  impression  to  the 
brain. 

Although  the  propagation  of  sound  is  quite  rapid,  it  is 
far  from  being  instantaneous.  Those  who  observe  the 
firing  of  a  gun  at  a  little  distance  notice  the  flash  of  light 
before  hearing  the  sound.  In  the  air,  sound  is  trans- 
mitted with  a  velocity  of  about  1180  feet  per  second  ;  in 
water,  the  velocity  is  four  times  as  great,  in  iron  ten 
times,  and  in  pine  wood  eighteen  times  as  great. 

The  ear  is  divided  into  three  parts :  the  external  ear 
includes  the  concha,  or  auditory  pavilion,  as  it  is  va- 
riously called,  and  a  canal  hollowed  out  in  the  temporal 
bone,  lined  with  skin,  and  called  the  external  auditory 
canal.  At  the  extreme  interior  of  this  canal  is  the 


ORGANS    OF    SENSE.  61 

tympanum,  a  fibrous   membrane   stretched  on  a  bony 
frame. 

The  middle  ear,  within  the  tympanum,  is  an  irregu- 
larly-shaped cavity,  containing  a  chain  of  four  little 
bones,  named  from  their  forms  the  hammer,  the  anvil, 
the  lenticular  bone,  and  the  stirrup.  This  chain  is  at- 

FIG.  33. 


A  VIEW  OP  ALL  THE  PARTS  OP  THE  EAR.— 1,  Meatus  or  canal ;  2,  the  mem- 
brana  tympani ;  3,  4,  5,  the  bones  of  the  ear ;  6.  membrane  of  the  foramen 
ovale ;  7,  the  central  part  of  the  labyrinth  (vestibule) :  8,  9, 10,  the  semi- 
circular canals ;  11,  12,  the  channels  of  the  cochlea ;  13,  auditory  nerve ; 
14,  the  opening  from  the  middle  ear,  or  tympanum,  to  the  throat  (Eu- 
stachian  tube). 

tached  at  one  end,  the  hammer  and  anvil,  to  the  tym- 
panum, and  by  the  other,  the  stirrup,  to  the  oval  window. 
The  oval  window  and  the  round  window  are  two  open- 
ings, each  closed  by  a  membrane,  which  establish  com- 
munication between  the  middle  and  the  internal  ears. 


62  A   COURSE   ON   ZOOLOGY. 

A  curvilinear  canal,  called  the  Eustachian  tube,  extends 
from  the  middle  ear  to  the  pharynx,  putting  the  middle 
ear  in  communication  with  the  external  air;  in  this 
manner  the  internal  face  of  the  tympanum  is  exposed  to 
the  same  pressure  as  the  external  face  to  which  the  air 
penetrates  through  the  external  auditory  canal. 

FIG.  34. 


A  VIEW  OP  THE  LABYRINTH  LAID  OPEN  (highly  magnified).—!,  1,  cochlea; 
2,  3,  two  canals  that  wind  two  and  a  half  turns  around  a  hollow  axis  (5) ;  7, 
vestibule;  8,  feneslra  rotunda;  9,  fenestra  ovalis;  11,  12,  13,  14,  15,  16,  17, 
18,  the  semicircular  canals. 

The  internal  ear,  or  labyrinth,  is  made  up  of  the  vesti- 
bule, three  semicircular  canals,  and  a  spiral  tube,  shaped 
like  a  snail-shell,  and  called  the  cochlea.  These  com- 
partments communicate  with  one  another,  and  are  filled 
with  a  liquid  in  which  terminate  the  delicate  filaments 
of  the  auditory  nerve ;  the  latter  enters  the  labyrinth 


ORGANS    OF    SENSE.  63 

through  the  internal  auditory  meatus,  which,  like  the  in- 
ternal and  middle  ear,  is  situated  in  the  hardest  part  of 
the  temporal  bone. 

^brations  of  the  air  are  collected  by  the  concha  and 
dir^Red  to  the  external  auditory  meatus,  gaining  in  force 
by  concentration.  The  tympanum  takes  up  the  vibrations 
and  transmits  them  to  the  chain  of  bones,  by  which  they 
are  exactly  reproduced  on  the  oval  window.  Here  they 
impress  the  liquid  in  the  labyrinth,  and,  reaching  the 
nerve  filaments,  produce  perception.  Such  is  the  mech- 
anism of  audition,  a  mechanism  so  perfect  that  the 
human  ear  can  distinguish  the  most  delicate  shades  of 
sounds  varying  between  thirty-two  and  seventy  thousand 
vibrations  per  second. 

Imperfect  hearing  usually  depends  on  too  great  tension 
of  the  tympanum,  or  a  want  of  elasticity  of  that  mem- 
brane. In  such  cases  hearing  is  improved  by  the  use 
of  ear-trumpets  which  concentrate  the  vibrations.  Deaf- 
ness caused  by  paralysis  of  the  auditory  nerve  or  similar 
accident  is  hopeless,  but  when  due  to  obstruction  of  the 
Eustachian  tube  or  of  the  external  meatus,  disappears 
under  appropriate  treatment. 

Sight. — The  sense  of  sight  acquaints  the  brain  with 
luminous  impressions,  and  gives  us  notions  of  the  color, 
form,  and  external  condition  of  bodies.  It  is,  of  course, 
dependent  on  the  eye. 

Lodged  in  the  upper  and  front  portion  of  the  face, 
surrounded  by  muscles  that  turn  it  at  will  in  any  direc- 
tion, the  eye  observes  from  far,  and  gathers  impressions 
of  all  that  exists  in  the  complete  hemisphere  embraced 
by  its  survey.  It  rests  on  a  fatty  cushion  at  the  bot- 
tom of  the  bony  cavity  of  the  orbit,  whose  thick  walls 
protect  it  effectually  on  the  sides,  while  the  eyebrows 


(J4 


A    COURSE    ON    ZOOLOGY. 


and  lashes  arrest  dust  that  might  enter  in  front.     The 

tears  with  which  its 

FIG.  35.  surface  is  continu- 

ally moistenec^re- 
vent  the  dryi^^ip 
of  its  membranes, 
and  during  sleep 
the  eyelids  cover  it 
as  with  a  sheath. 

The  eyeball  is 
covered  exteriorly 
with  a  hard,  white, 
opaque  membrane, 
called  the  sclerotic 
coat,  in  the  centre 
of  which  is  inserted 
a  thick,  _  perfectly 
transparent  disk, 
much  like  the  crys- 
tal of  a  watch. 
Within  this  mem- 
brane, which  is 
named  the  cornea, 
is  seen  a  variously- 


MUSCLES  OF  THE  EYE.— 1,  the  palpebral  elevator ; 
2,  the  trochlear  muscle  ;  3,  the  pulley  through 
which  the  tendon  of  insertion  plays ;  4,  supe- 
rior rectus  muscle;  5,  inferior  rectus  muscle; 
6,  external  rectus  muscle ;  7, 8,  its  two  points 
of  origin ;  9,  interval  through  which  pass  the 
oculo-motor  and  abducent  nerves ;  10,  inferior 
oblique  muscle ;  11,  optic  nerve ;  12,  cut  surface 
of  the  malar  process  of  the  superior  maxillary 
bone;  13,  the  nasal  notch;  A,  the  eyeball. 


colored  circle,  called 

the  iris,  in  whose  centre  is  a  round  opening,  the  pupil. 
The  pupil  is  the  window  by  which  the  light  enters  ;  it  en- 
larges  or  contracts  by  the  play  of  the  muscular  fibres  com- 
posing the  iris,  thus  allowing  the  entrance  of  a  larger  or 
smaller  amount  of  light,  as  may  be  required  for  vision.  A 
transparent  liquid,  called  aqueous  humor,  fills  the  space 
in  front  of  the  iris,  and  behind  it  to  the  crystalline  lens, 
a  sort  of  kernel  composed  of  a  gelatinous,  transparent 


ORGANS   OF   SENSE.  65 

substance.  Then  comes  the  vitreous  humor,  transparent 
but  much  firmer  than  the  aqueous  humor,  and  behind  it, 
in  the  form  of  a  delicate  film,  the  retina  which  is  the 
termination  of  the  optic  nerve.  The  retina  is  at  the 

FIG.  36. 


VERTICAL  SECTION  ANTEEO-POSTERIORLY  OF  THE  EYEBALL.— 1,  optic  nerve; 
2,  sclerotic ;  3.  its  posterior  thicker  portion ;  4,  sheath  of  the  optic  nerve 
continuous  with  the  sclerotic ;  5,  the  nerve  within  the  sheath  ;  6,  insertion 
of  the  recti  muscles  into  the  sclerotic ;  8,  8,  superior  and  inferior  recti 
muscles;  9,  cornea ;  10,  its  conjunctival  surface ;  11,  aqueous  humor;  12, 13, 
bevelled  edge  of  the  cornea  fitting  into  the  sclerotic ;  14,  circular  sinus  of 
the  iris;  15,  choroid ;  16,  the  anterior  portion,  constituting  the  ciliary 
body ;  17,  the  ciliary  muscle ;  18,  the  ciliary  processes ;  19,  retina ;  20,  its 
origin ;  21,, the  ora;  22,  central  retinal  artery;  23,  vitreous  humor;  24,  25, 26, 
hyaloid  tunic;  27,  suspensory  ligament  of  the  crystalline  lens,  28;  29,  iris ; 
30,  pupil ;  31,  posterior  chamber,  and  32,  anterior  chamber,  occupied  by  the 
aqueous  humor. 

back  of  the  eye,  resting  on  a  deep  black  membrane 
called  the  choroid,  which  absorbs  the  indirect  rays  of 
light,  and  prevents  them  from  disturbing  by  reflec- 
tion the  sharpness  of  the  luminous  image  on  the  retina. 
The  iris  and  the  frame  holding  the  crystalline  lens, 
e  6* 


66 


A   COURSE   ON   ZOOLOGY. 


FIG.  37. 


and  called  the  ciliary  process,  are  really  folds  of  the 
choroid. 

The  eyelids  are  formed  by  folds  of  the  skin,  and  their 
movements  are  controlled  by  several  muscles.  They  are 
sustained  by  a  thin  cartilage,  the  tarsal  cartilage,  and 
their  borders  are  fringed  by  the  lashes.  Little  glands 
contained  within  the  upper  eyelid  secrete  a  viscous  liquid 
that  aids  the  lashes  in  arresting  dust. 
The  lachrymal  apparatus  which  supplies  the  tears  is 

composed  :  1st,  of  the  lach- 
rymal gland,  situated  in  the 
superior  and  external  por- 
tion of  the  orbit,  and  dis- 
tributing by  six  or  seven 
ducts  its  secretion  over  the 
internal  surface  of  the  up- 
per eyelid  ;  2d,  of  the  nasal 
duct,  placed  in  the  inferior 
and  internal  angle  of  the 
orbit,  and  carrying  the  ex- 
cess  of  secretion  to  the  in- 
terior  of  the  nasal  fosses. 

of  the  Meibomian  glands;  3,  the  As  an  Optical  apparatus  the 

cartilage  of  the  lower  eyelid,  also  functions  like  the  pho- 

showing  on  its  border  the  open-  J 

ings  of  the  Meibomian  glands;  4,5,  tOgrapher's    Camera.      Pho- 

the  lachrymal  gland;  6,  its  ducts;  tographers  place  a  Sensitive 

7,  the  plica  semilunaris  ;  8,  the  ca-  »                                                    . 

runcula  lachrymalis  ;  9,  the  puncta  plate  —  that   IS,   One    that   IS 

lachrymalia,  opening  into  the  lach-  capable    of   being  acted  On 

rymal  canals;  10,  11,  the  superior  ° 

and  inferior  lachrymal  canals;  12,  by  light  —  at  the   back  Ot  a 

the  lachrymal   sac;   13,  the  nasal  box   blackened    inside,    and 

duct,  terminating  at  14  in  the  lower  „    ,                                  A  ,      ,  , 

meatusofthenose.  called   a   camera.     At    the 

front  of  the  box  is  an  aper- 
ture into  which  is  fitted  a  tube,  called  the  objective,  hold- 


THE  APPENDAGES  OP  THE  EYE—  i,  the 


ORGANS   OP   SENSE.  67 

ing  one  or  more  glass  lenses,  which  project  on  the  sensi- 
tive plate  the  luminous  rays  coming  from  the  object  to 
be  photographed. 

The  eye,  lined  with  the  choroid,  is  comparable  to  the 
camera.  The  crystalline  lens  is  the  objective,  for  it  is  a 
convex  lens,  and  the  nervous  membrane,  the  retina,  is 
the  sensitive  plate  on  which  the  images  of  objects  before 
the  eyes  are  reproduced. 

In  normal  vision  the  form  of  the  crystalline  lens  is 
such  that  the  luminous  rays  passing  through  it  make 
their  sharpest  image  on  the  retina.  Short-sightedness  is 
due  to  too  great  a  convexity  of  the  different  lenses  that 
the  light  traverses  before  reaching  the  retina ;  the  image 
is  then  produced  in  front  of  the  retina,  and  objects  are 
not  distinctly  perceived  unless  they  are  placed  near  the 
eye.  Far-sightedness  depends,  on  the  contrary,  on  too 
great  flatness  of  the  lenses  of  the  eye :  the  image  would 
be  more  distinct  behind  the  retina,  and  objects  can  be 
seen  most  distinctly  when  at  some  distance.  Under 
ordinary  conditions  the  distance  at  which  small  objects 
are  most  distinctly  seen  without  straining  the  eyes  is 
ten  inches.  This  distance  may  fall  to  less  than  eight 
inches  in  near-sightedness,  or  may  be  as  great  as  thirty 
inches  in  far-sightedness.  Myopia  or  near-sightedness 
may  diminish  as  age  increases,  but  presbyopia  or  far- 
sightedness always  increases.  These  two  infirmities  are 
corrected  by  the  use  of  glasses,  either  concave  or  convex, 
as  the  fault  of  the  crystalline  lens  is  too  great  or  too 
little  convexity. 


68  A   COURSE   ON    ZOOLOGY. 

CHAPTER  VII. 
Functions  of  Locomotion — Organs  of  Speech. 

WE  must  now  consider  the  skeleton  as  the  solid  frame- 
work of  the  body,  serving  for  the  attachment  of  the 
muscles,  and  furnishing  points  of  resistance  for  their 
contractions. 

The  skeleton  is  a  system  of  bones,  Bones  are  com- 
posed of  a  gelatinous  matter,  hardened  by  the  deposit  of 
a  calcareous  mineral  matter  in  its  substance.  In  an 
adult  the  gelatinous  matter  represents  only  a  third" of  the 
total  weight  of  the  bones,  the  remaining  two-thirds  con- 
sisting of  mineral  matter ;  but  early  in  life  the  mineral 
matter  is  present  only  in  small  proportion.  Then  many 
parts  of  the  bones  have  but  a  cartilaginous  structure  ;  an 
example  is  seen  in  the  fontanels  in  the  skull  of  a  very 
young  child,  and,  on  account  of  the  close  proximity  of 
the  brain,  shocks  to  the  head  are  then  very  dangerous. 
The  gradual  hardening  of  the  bones  by  calcareous  mat- 
ter is  called  ossification,  and  ossification  is  only  com- 
pleted towards  the  time  of  the  complete  development  of 
the  individual, — that  is,  towards  adult  life.  The  bony  sub- 
stance does  not  present  throughout  its  mass  the  same 
characteristics.  In  some  parts  it  is  hard,  compact,  and 
strong,  resembling  ivory ;  in  others  it  is  spongy,  being 
perforated  with  holes  throughout.  Ordinarily  the  ex- 
terior portions  of  the  bones  are  made  up  of  compact 
tissue,  while  the  interior  portions  and  extremities  are 
composed  of  spongy  tissue. 

The  bones  have  been  classified  as  of  three  kinds,  ac- 


FUNCTIONS   OF   LOCOMOTION.  69 

cording  to  their  forms  and  structures :  long  bones,  flat 
bones,  and  short  bones. 

As  their  name  indicates,  the  long  bones  are  elongated. 
At  each  end  they  have  an  enlargement, — head  or  epiph- 
ysis, — the  interior  of  which  is  composed  of  spongy 
tissue.  Between  these  is  the  shaft  of  the  bone  or  diaph- 
ysis,  made  up  exclusively  of  compact  tissue,  and  hav- 
ing a  central  canal,  the  medullary  canal,  in  which  is  the 
marrow.  The  structure  of  the  long  bones  combines  all 
the  conditions  of  lightness  and  strength,  for  these  bones 
act  as  levers  for  the  great  movements.  The  bones  of  the 
upper  arm  and  forearm,  and  those  of  the  thigh  and  leg, 
belong  to  this  class. 

The  flat  bones  have  considerable  surface ;  they  contain 
practically  no  spongy  tissue,  and  this  accounts  for  their 
great  strength.  They  occur  particularly  in  those  parts 
of  the  body  where  the  bony  system  is  required  to  protect 
other  organs :  they  form  the  envelope  of  the  skull,  the 
pelvis,  etc. 

The  short  bones  are  composed  of  spongy  tissue  in  the 
interior,  covered  by  a  thin  layer  of  compact  tissue.  They 
are  not  large,  having  about  the  same  dimensions  in  all 
directions,  and  several  of  them  are  usually  arranged  to- 
gether in  places  where  only  small  movement  is  required, 
as  in  the  wrist  and  the  instep  of  the  foot ;  the  vertebral 
column  is  composed  entirely  of  bones  of  this  class. 

On  the  surfaces  of  the  bones  are  found  ridges  or  crests 
for  the  insertion  of  the  muscles,  apophyses  or  condyles 
for  reciprocal  articulation,  and  numerous  holes  that  serve 
for  the  passage  of  nerves  and  nourishing  vessels.  Their 
tissue  has  great  vitality,  a  proof  of  which  is  shown  by  the 
rapidity  with  which  the  broken  ends  are  mended  in  case 
of  fracture,  by  the  formation  of  new  tissue  called  callus, 


70 


A  COURSE  ON  ZOOLOGY. 


The  name  articulation  is  given  to  the  joining  or  fitting 
together  of  the  bones.  All  the  bones  of  the  human  body, 
with  a  single  exception,  the  hyoid  bone,  are  joined  or 
articulated  together  in  the  solid  framework,  called  the 
skeleton.  The  manner  of  articulation  varies  accord- 
ing to  the  kind  of  move- 
*•  38.  ment  that  must  take  place. 

FIG.  38a. 


STRUCTURE  OF  A  LONG  BONE.— a, 
head  or  epiphysis,  filled  with 
spongy  tissue;  6,  body  or  diaph- 
ysis. 


VERTICAL  SECTION  OF  THE  KNEE- 
JOINT.— 5,  tibia;  1,  femur;  3,  pa- 
tella ;  2,  4,  tendon,  enclosing  the 
articulation  in  front  and  en- 
closing the  patella ;  e,  ligament 
of  the  articulation;  s,  synovial 
membrane  forming  the  articular 
capsule. 


There  are  three  principal  kinds  :  fixed  articulation,  mixed 
articulation,  and  mobile  articulation, 

In  the  fixed  articulation  the  bones  are  so  joined  as  to 
be  incapable  of  any  movement  one  on  the  other ;  they 
sometimes  are  joined  by  smooth  edges,  sometimes  by 
notches  that  dovetail  together.  Such  are  the  articula- 
tions of  the  cranial  bones. 

In  mixed  articulation  the  bones  do  not  touch,  but  are 


FUNCTIONS   OF   LOCOMOTION. 


71 


joined  by  an  intermediate  fibrous  and  elastic  tissue,  which 
allows  a  certain  amount  of  motion.  The  short  bones  are 
articulated  together  in  this  manner. 

In  the  mobile  articulation  the  extremities  of  the  bones 
that  come  together  are  free  ;  they  touch  by  surfaces  re- 
ciprocally concave  and  convex,  each  being  covered  by  a 

FIG.  39. 


BONES  OF  THE  HEAD.— 1,  frontal  bone;  2,  parietal  bone;  3,  temporal  bone; 
4,  occipital  bone ;  5,  nasal  bone ;  6,  malar  bone ;  7,  upper  jaw ;  8,  os  unguis ; 
9,  lower  jaw  (maxilla). 

cartilaginous  pad.  This  pad  facilitates  the  gliding  of  the 
surfaces  one  on  the  other,  and  the  friction  is  still  further 
diminished  by  a  viscous  liquid,  called  synovial  fluid,  se- 
creted by  synovial  capsules,  membranes  that  surround 
all  mobile  articulations.  Strong  fibrous  cords,  called  lig- 
aments, are  attached  to  the  extremities  of  both  articu- 
lating bones,  and  hold  the  ends  in  position.  Motion  is 


72  A   COURSE   ON   ZOOLOGY. 

very  easy  in  articulations  of  this  class,  which  is  the  gen- 
eral method  for  the  long  bones. 

The  Skeleton. — We  must  limit  ourselves  to  a  very  brief 
description  of  the  different  regions  of  the  skeleton  ;  these 
are  three  in  number,  the  head,  the  trunk,  and  the  limbs. 

The  bones  of  the  head  are  classified  as  those  of  the 
skull  and  those  of  the  face.  Those  of  the  skull  form  a 
box  in  which  the  brain  is  enclosed.  They  are  eight :  the 
frontal  bone  of  the  forehead,  the  occipital  behind,  the 
parietal  bones  forming  the  top  of  the  head,  the  temporals 
at  the  sides  or  temples,  the  sphenoid  below,  and  the  eth- 
moid in  front,  and  dovetailed  into  the  frontal.  There 
are  fourteen  bones  in  the  face ;  several — among  which  are 
the  palatine  and  turbinated  bones  of  the  nose,  the  lach- 
rymals and  the  vomer — are  not  shown  in  the  accompany- 
ing figure,  either  because  they  are  situated  in  the  inte- 
rior, or  because  they  are  too  small ;  but  there  are  shown 
the  inferior  maxillary  bone,  which  forms  the  lower  jaw, 
the  two  superior  maxillary  bones  which  make  up  the 
upper  jaw,  the  two  malars  or  cheek  bones,  and  the  nasal 
bones  that  form  the  sides  of  the  nose. 

Among  the  bones  of  the  head  must  be  mentioned  the 
hyoid  bone,  a  small  isolated  bone  that  supports  the 
tongue,  and  gives  rigidity  to  the  upper  part  of  the  respi- 
ratory apparatus. 

The  bones  of  the  trunk  include  the  vertebral  column, 
the  ribs,  the  sternum,  and  the  pelvis. 

The  middle  part  of  the  vertebral  column  with  the  ribs 
and  sternum  constitute  the  thorax,  a  sort  of  bony  cage 
that  encloses  the  principal  organs  of  circulation  and  res- 
piration. The  lower  portion  of  the  vertebral  column, 
with  the  iliac  bones,  which  project  at  the  hips,  forms  a 
strong  bony  belt  for  the  support  and  protection  of  the 


FUNCTIONS    OF    LOCOMOTION. 


73 


digestive  organs.     The  vertebral  column  is  composed  of  a 
series  of  small  bones  called  vertebrae.     The  vertebrae  are 


FIG.  40. 


FIG.  40a. 


A     VERTEBRA     OF      THE      NECK.— 1, 

body;  2,  foramen;  4,  spinous 
process,  cleft  at  its  extremity; 
5,  transverse  process;  7,  inferior 
articulating  process;  8,  superior 
articulating  process. 


A  LUMBAR  VERTEBRA.— 1,  the  carti- 
laginous  substance  that  connects 
the  bodies  of  the  vertebrae;  2, 
body;  3,  spinous  process;  4,  4, 
transverse  processes ;  5,  5,  articu- 
lating processes ;  7,  foramen. 


placed  one  on  another,  and  are  separated  by  cushions  of 
fibro-cartilagmous  tissue  that  allows  a  certain  degree  of 
movement  to  the  articulation.  Figures  40  and  40a  repre- 
sent two  of  these  small  bones.  The  vertebral  column 
is  divided  into  five  regions.  In  man  there  are  seven 
vertebrae  in  the  neck,  twelve  in  the  back,  five  in  the 
loins,  five  others  firmly  articulated  in  a  single  piece  in 
the  sacrum,  and  two  or  three  that  are  quite  rudimentary 
in  the  coccyx.  In  animals,  these  last  are  ordinarily 
much  more  numerous,  much  more  developed,  and  form 
the  framework  of  the  tail. 

In  man  there  are  twenty-four  ribs,  twelve  on  each  side 
of  the  chest.     They  are  articulated  with   the  vertebrae 
behind  and  with  the  sternum  in  front,  but  they  are  con- 
nected with  the  latter  only  by  cartilaginous  prolonga- 
i>  7 


74 


FIG.  41. 


THE  SKELETON. 


FUNCTIONS   OF   LOCOMOTION. 


75 


TABLE  OF  THE  BONES. 


HEAD  (22) 


Skull  (8) 


Face  (14) 


CERVICAL  REGION  (8) ... 
THORAX  (37)   .  .  . 


UPPER  EXTREMITIES  (64)  ... 


LUMBAR  REGION  (5) 
PEL  vis  (4)    .... 


LOWER  EXTREMITIES  (60) 


Frontal  (forehead). 

2  Temporal  (temples). 

2  Parietal  (side). 

Occipital  (posterior  base). 

Sphenoid  (base). 

Ethmoid  (base  of  nose). 

2  Superior  maxillae  (upper  jaw). 

2  Nasal  (bridge  of  nose). 

2  Malar  (cheek). 

2  Lachrymal  (corner  of  orbit). 

2  Turbinated  (within  nostrils). 

2  Palate  (posterior  hard  palate). 

Vomer  (nasal  partition). 

Inferior  maxilla  (lower  jaw). 

7  Cervical  vertebrae  (neck). 

Hyoid  bone  (base  of  tongue). 

14  True,  6  False,  4  Floating  ribs. 

12  Dorsal  vertebrae  (back). 

Sternum. 

Shoulder  .    J  Clavicle  (collar). 

I  Scapula  (shoulder-blade). 
Arm  f  Humerus  (arm). 

I  Radius,  Ulna  (forearm). 

(  8  Carpal  (wrist). 
Hand .  .   .    j  5  Metacarpal  (hand). 

[14  Phalanges  (fingers). 
5  Lumbar  vertebrae  (loins). 
2  Innominata. 
Sacrum. 
Coccyx. 

Thigh     .  .    ( Femur. 
,  J  Patella  (knee-pan). 

'   I  Tibia  (large  bone). 

1  Fibula  (outer  bone). 


Foot   . 


[  7  Tarsal  (instep,  heel), 
j  5  Metatarsal  (arch). 
1 14  Phalanges  (toes). 


76  A   COURSE   ON   ZOOLOGY. 

tions,  and  so  possess  a  very  considerable  freedom  of 
motion. 

The  sternum  is  a  flat  bone,  shaped  like  a  dagger,  in  the 
front  of  the  thorax  and  in  the  median  line.  It  is  con- 
nected with  the  ribs,  and  also  with  the  collar-bones  or 
clavicles,  to  which  it  affords  a  central  support. 

The  iliac  bones  are  large  flat  bones ;  they  are  articu- 
lated together  in  front,  and  with  the  sacrum  behind,  and 
they  form  the  floor  of  the  trunk. 

The  upper  and  lower  limbs  are  very  analogous  in  the 
number  and  arrangement  of  the  bony  pieces  that  com- 
pose them.  The  hand  corresponds  exactly  to  the  foot, 
the  forearm  to  the  leg,  the  arm  to  the  thigh,  the  shoul- 
der to  the  pelvis,  which  latter  may  be  considered  ana- 
tomically as  forming  part  of  the  lower  limbs.  While 
there  are  certain  differences  in  form  and  in  the  apparent 
number  of  corresponding  bones  in  the  upper  and  lower 
limbs,  these  differences  are  due  to  the  difference  in  func- 
tion. 

The  upper  limb  includes  the  shoulder,  the  arm,  the 
forearm,  and  the  hand. 

The  bones  of  the  shoulder  are  a  large  flat  bone  fitting 
close  to  the  back,  and  called  the  scapula  or  shoulder- 
blade,  and  the  clavicle,  or  collar-bone,  forming  a  sort 
of  bow  in  front,  and  articulated  with  the  sternum  and 
the  scapula.  This  bone  is  frequently  broken  by  falls, 
but  its  fracture  is  repaired  with  great  facility. 

The  arm  contains  but  one  bone,  the  humerus.  This  is 
articulated  with  the  scapula  in  such  a  manner  that  it 
possesses  a  freedom  of  motion  so  great  as  to  allow  it  to 
make  a  complete  rotation  on  its  axis. 

The  forearm  is  composed  of  two  bones, — the  radius, 
towards  the  outside,  and  the  ulna,  on  the  inside.  The 


FUNCTIONS   OF   LOCOMOTION.  77 

latter  is  the  only  one  which  is  articulated  with  the 
humerus;  its  upper  end  forms  the  projection  of  the 
elbow.  The  other  bone,  the  radius,  is  articulated  with 
the  ulna  above,  and  by  its  lower  extremity  supports  the 
hand;  it  turns  freely  around  the  ulna.  This  simple 
but  ingenious  mechanism  allows  us  to  make  easily  the 
various  movements  and  changes  of  position  of  the  hand. 

The  hand  includes  the  wrist  or  carpal  bones,  eight  in 
number,  and  all  belonging  to  the  class  of  short  bones, 
the  five  metacarpal  bones  that  form  the  framework  of 
the  palm  of  the  hand,  and  the  phalanges,  of  which  there 
are  three  in  each  finger,  except  the  thumb,  which  has 
only  two. 

The  lower  limb,  correctly  speaking,  is  composed  of  the 
thigh,  the  leg,  and  the  foot. 

The  femur,  or  thigh-bone,  is  articulated  with  the  iliac 
bone  above,  and  with  the  tibia  below.  It  is  the  largest 
bone  of  the  skeleton.  Its  somewhat  arched  form  con- 
tributes to  increase  the  supporting  base  of  the  body,  and 
renders  the  erect  position  easier. 

The  leg  has  two  bones, — the  tibia,  inside,  and  the  fibula, 
outside  ;  the  latter  takes  but  a  secondary  part.  The  ar- 
ticulation of  the  tibia  and  femur  is  protected  by  the  pa- 
tella or  knee-pan,  a  small,  flat  bone,  in  which  anatomists 
find  the  analogue  of  the  eminence  of  the  ulna,  which 
forms  the  elbow. 

The  foot  includes  the  tarsal  bones,  of  which  there  are 
but  seven  (two  of  them  are  joined  together  in  a  single 
bone  that  forms  the  heel-bone  or  calcaneum).  five  meta- 
tarsal  bonos  like  the  metacarpals,  and  the  phalanges  of 
the  toes  corresponding  in  number  and  distribution  to 
those  of  the  fingers. 

Locomotion. — The  study  of  locomotion  is  that  of  the 

7* 


78  A   COURSE   ON   ZOOLOGY. 

changes  of  position  of  the  body  in  space.  These  changes 
are  produced  according  to  the  general  laws  of  mechanics ; 
they  result  from  the  action  of  certain  forces  on  various 
systems  of  cords  and  levers.  In  animal  mechanics  the 
bones  represent  levers,  the  muscles  are  cords,  and  the 

FIG.  42. 


DIAGRAM  OF  THE  THIRD  ORDER  OF  LEVER.—!,  the  bone  of  the  arm  above  the 
elbow ;  2,  one  of  the  bones  below  the  elbow ;  3,  the  muscle  that  bends  the 
elbow ;  this  muscle  is  united,  by  a  tendon,  to  the  bone  below  the  elbow  (4) ; 
at  the  other  extremity,  to  the  bone  above  the  elbow  (5) ;  6,  the  muscle  that 
extends  the  elbow  ;  7,  its  attachment  to  the  point  of  the  elbow ;  8,  a  weight 
in  the  hand  to  be  raised.  The  central  part  of  the  muscle  3  contracts,  and 
its  two  ends  are  brought  nearer  together.  The  bones  below  the  elbow  are 
brought  to  the  lines  shown  by  9, 10,  11.  The  weight  is  raised  in  the  direc- 
tion of  the  curved  line.  When  the  muscle  6  contracts,  the  muscle  8  relaxes, 
and  the  forearm  is  extended. 


nervous  system  by  its  motor  fibres  acts  as  the  cause  of 
the  movements. 

The  muscles  are  composed  for  the  most  part  of  a 
special  tissue  having  contractile  power,  called  muscu- 
lar tissue,  and  their  contractile  activity  is  excited  by 
impulses  from  the  nervous  system.  Movements  result 
from  the  change  of  position  of  the  long  levers  to  which 


FIG.  43. 


79 


80 


FIG.  44. 


FUNCTIONS    OF    LOCOMOTION.  81 


TABLE  OF  THE   PRINCIPAL  SKELETAL   MUSCLES. 
(See  Figs.  43  and  44.) 

THE  HEAD. 

Occipito-frontalis,  moves  the  scalp. 
Orbicularis  palpebrarum,  closes  the  eye. 
Orbicularis  oris,  closes  the  lips. 


Temporal,  /  elevate  the  lower  jaw' 
Digastric,  depresses  the  lower  jaw. 

THE  NECK. 

Sterno-cleido-mastoid,  moves  the  head  forward  or  to  one  side. 
Trapezius  (7),  moves  the  head  and  neck  backward. 

THE  TRUNK  (anterior). 
Diaphragm,  muscle  of  respiration. 
Pectoralis  major,  moves  the  humerus  and  scapula. 
Serratus  magnus,  aids  in  violent  respiration. 
Intercostals,  muscles  of  respiration. 
Rectus  abdominis,  \  , 

Psoas  magnus,       /  bend  the  body  forward' 
Obliquus  externus  (26), )  assists  in  violent  expiration. 
Obliquus  internus,        *  bends  the  body  forward. 

THE  TRUNK  (posterior). 
Rhemboideus  major,  \ 

Rhomboideus  minor,  /  move  the  Scapula  backward- 
Latissimus  dorsi  (24),  moves  the  humerus  downward  and  backward. 
Serratus  posticus  inferior,  muscle  of  expiration. 

THE  UPPER  EXTREMITY. 
Deltoid  (8),  elevates  the  arm. 
Subscapularis,         -\ 

Supraspinatus,        v  rotate  the  humerus. 
Infraspinatus  (12),  > 
Brachialis  anticus, }   „ 
Biceps,  '}  flex  the  forearm. 

Triceps  (10), ) 

Anconeus,    j  extend  the  forearm. 

Flexor  carpi  ulnaris  and  radialis,  move  the  carpus. 

Flexor  digitorum,  flexes  the  fingers. 

Extensor  carpi  radialis  and  ulnaris  (21),  antagonize  the  flexors. 

Extensor  digitorum  (22),  antagonizes  the  flexors. 

(Upward  of  thirty  muscles  act  on  the  fingers.) 


82  A   COURSE   ON    ZOOLOGY. 


THE  LOWER  EXTREMITY. 

rotate  ""  thlgh'move  the 


Glutxus  minimus, 

Psoas  magnus,       ) 

Pectineus,  I  raise  the  thigh.    When  the  limbs  are  flexed,  bend  the 

Iliacus,  body  forward. 

Adductor  longus,   J 

Rectusfemons,  ^  extend  the  leg.   Their  common  tendons  (quad- 

(      ricepsfemoris)  contain  the  patella. 
Vastus  externus  and  internus,  > 

Sartorius  (tailor's  muscle),  flexes  the  leg  on  the  thigh. 
Biceps  femoris,  \ 

Semi-tendinosus  (30),  >-  flex  the  leg. 
Semi-membranosus,    J 


Tibialis  anticus,    1 

Proprius  pollute.  I  fl 

Gcustrocnemius  (32),  )  ftcting  through  the  fendo  Acmis,  extend  the  foot. 

&Ol€US) 

Extensor  digitorum,  j 
Flexor  digitorum,      > 

Upward  of  twenty  muscles  act  on  the  toes.) 

the  extremities  of  the  muscles  are  attached,  and  which 
are  drawn  together  or  separated  by  the  contractions. 

The  movements  of  extension,  as  well  as  those  of 
flexure  of  the  members,  are  produced  by  muscular  con- 
traction, the  difference  depending  on  the  position  of  the 
points  of  insertion  of  the  muscles  ;  in  the  hand,  for  ex- 
ample, the  extensor  muscles  are  attached  to  the  dorsal 
or  back  surfaces  of  the  phalanges,  while  the  flexor  mus- 
cles are  attached  to  the  interior  surfaces.  The  contrac- 
tions of  the  extensors  compel  the  fingers  to  straighten 
out,  while  those  of  the  flexors  bend  them  in  against  the 
palms.  Those  muscles  are  called  antagonistic  of  which 
the  actions  are  thus  opposed  the  ones  to  the  others, 
and  those  whose  actions  combine  to  produce  a  common 
movement  are  said  to  be  congenerate. 


FUNCTIONS   OP   LOCOMOTION.  83 

Muscular  tissue  is  composed  of  parallel  fibres  arranged 
in  bundles.  The  fibres  are  of  microscopic  dimensions, 
and  the  separate  bundles  are  all  enveloped  by  a  fibrous 
covering,  called  aponeurosis ;  an  envelope  of  the  same 
nature  surrounds  the  whole  muscle  and  isolates  it  from 
the  surrounding  parts. 

Ordinarily  the  muscles  have  elongated  forms,  like 
spindles ;  the  middle  portion,  composed  of  muscular  tis- 
sue, strictly  speaking,  is  red  and  fleshy,  and  constitutes 
the  meat  of  edible  animals.  The  two  extremities  of  the 
muscle  are  formed  of  a  very  strong,  white,  pearly  sub- 
stance, and  this  is  a  direct  continuation  of  the  periosteum 
or  fibrous  envelope  covering  the  bones.  The  end  of  the 
muscle  connected  with  the  bone  which  the  muscle  moves 
is  usually  elongated  like  a  cord,  is  called  the  tendon,  and 
is  the  origin  of  the  muscle ;  that  end  which  is  attached 
to  the  fixed  bone  is  usually  wide  and  flattened,  and  forms 
what  is  called  the  aponeurosis  of  insertion. 

•The  life  of  the  muscles  is  very  active,  and  they  there- 
fore receive  many  blood-vessels.  They  are  also  provided 
with  many  nervous  filaments,  but  most  of  these  are  from 
the  motor  system,  and  the  sensibility  is  not  highly  de- 
veloped. 

We  cannot  enter  into  details  concerning  the  muscles. 
These  organs,  which  number  more  than  four  hundred, 
are  symmetrically  arranged,  and  usually  by  pairs.  They 
form  several  superposed  layers.  Figures  43  and  44  show 
the  superficial  muscles  of  the  trunk, — that  is,  those 
which  in  this  region  are  placed  immediately  under  the 
skin. 

So  far  as  their  primary  action  is  concerned,  the  muscles 
are  divided  into  two  classes : 

1.  Those  whose  action  is  controlled  by  the  will,  such 


84  A   COURSE   ON   ZOOLOGY. 

as  those  of  the  limbs,  of  the  face,  etc.  These  are  volun- 
tary muscles. 

2.  Those  whose  action  cannot  be  controlled  by  the 
will,  such  as  those  of  the  heart,  of  the  muscular  coats  of 
the  intestines  and  stomach,  etc.  These  are  involuntary 
muscles. 

The  differences  in  individual  vigor  are  essentially  de- 
pendent on  the  greater  or  less  development  of  the  mus- 
cular system.  This  development  may  be  natural,  but  it 
is  frequently  the  result  of  suitable  exercise  and  appro- 
priate diet  and  habit  of  life.  So  physicians  prescribe  for 
young  persons  of  deficient  development  different  exer- 
cises for  the  body,  such  as  fencing,  boxing,  swimming, 
etc.  The  ancients  formed  their  athletes  in  the  same 
manner,  and  even  our  horses  are  not  permitted  to  com- 
pete at  the  races  without  previous  training. 

The  contraction  of  a  set  of  muscles  cannot  be  pro- 
longed beyond  a  certain  time,  always  quite  limited.  A 
continuation  of  the  state  of  contraction  brings  about 
fatigue,  and  the  necessity  for  a  cessation  of  the  muscular 
tension. 

As  for  the  involuntary  muscles,  their  intermittent 
action  continues  throughout  the  course  of  life  without 
producing  any  direct  sensation  of  fatigue ;  and  yet,  to  give 
but  a  single  example  of  the  work  they  accomplish,  the 
heart  beats  about  one  hundred  thousand  times  a  day. 

The  Voice  and  Vocal  Apparatus. — The  sounds  which 
constitute  the  human  voice  are  produced  by  the  passage 
of  the  air  expelled  from  the  lungs  through  a  very  simple 
apparatus  called  the  larynx. 

This  apparatus  is  in  the  upper  part  of  the  trachea,  and 
is  a  tube  formed  by  the  union  of  a  number  of  elastic, 
cartilaginous  rings,  separated  from  the  pharynx  by  the 


ORGANS    OF    SPEECH. 


85 


FIG.  46. 


hinged  cover  called  the  epiglottis.  The  interior  of  the 
tube  is  lined  with  a  continuation  of  the  mucous  mem- 
brane of  the  mouth. 

The  cartilages  that 
help  form  the  larynx 
are  the  thyroid  in  front, 
the  cricoid  below  and 
behind,  and  the  two 
arytenoids  above  and 
behind.  These  parts 
are  joined  by  ligaments 
that  allow  some  motion, 
and  by  certain  muscles 
that  somewhat  change 
their  respective  posi- 
tions. The  more  im- 
portant ligaments,  and 
the  only  ones  that  are 
indispensable  for  the 
formation  of  the  voice, 
are  the  inferior  liga- 
ments or  vocal  cords; 
these  are  more  or  less 
stretched,  and  closer 
together  or  farther 
apart,  according  to  the 
movements  given  by 
the  muscles  of  the 
larynx  to  the  different  cartilages.  The  opening  between 
them  through  which  the  air  passes  is  called  the  glottis. 
During  the  production  of  vocal  sound,  the  form  of  the 
glottis  is  a  narrow  slit ;  when  at  rest,  the  opening  is 
triangular.  Above  the  vocal  cords  are  two  other  liga- 

8 


FRONT  VIEW  OF  THE  LARYNX.— 1,  hyoid 
bone ;  2,  greater  cornu ;  3,  small  cornu ; 
4,  lateral  thyro-hyoid  ligament;  5,  nod- 
ular cartilage ;  6,  middle  thyro-hyoid 
ligament;  7,  thyroid  cartilage;  8,  su- 
perior horn  ;  9,  inferior  horn ;  10,  cricoid 
cartilage ;  11,  crico-thyroid  ligament;  12, 
crico-ary-thyroid  ligament;  13,  14,  first 
and  second  rings  of  the  trachea. 


86 


A  COURSE  ON  ZOOLOGY. 


ments,  much   more  relaxed,  and  the  opening  between 
them  is  not  nearly  so  narrow  as  that  between  the  vocal 

cords.     These  are  the 
ligaments, 
the     upper 


Fro.  46. 


superior 

Between 

and    lower    ligaments 

on   each  side    are  the 

spaces      or       cavities 

called    the    ventricles 

of  the  larynx. 

Mutes  are  persons 
deprived  of  the  power 
of  articulate  speech 
or  of  producing  any 
definite  sound.  This 
infirmity  may  result 
from  paralysis  of  the 
nerves  which  control 
the  movement  of  the 
parts  of  the  vocal  ap- 
paratus, but  complete 
loss  of  speech  is  of 
rare  occurrence  ex- 
cepting in  cases  of 
idiocy  or  in  those  born 
deaf.  It  then  is  caused 
by  a  complete  absence 
of  the  sense  of  hearing 
and  the  consequent  impossibility  of  acquiring  the  princi- 
ples of  language. 


BACK  VIEW  OF  THE  LARYNX.— 1,  thyroid  car- 
tilage ;  2,  superior  horn ;  3,  inferior  horn  ; 
4,  cricoid  cartilage ;  5,  crico-thyroid  liga- 
ment; 6,  arytenoid  cartilage;  7,  promi- 
nent external  angle  of  the  base  into  which 
the  crico-arytenoid  muscles  are  inserted  ; 
8,  epiglottic  cartilage;  9,  thyro-epiglottic 
ligament ;  10,  posterior  membrane  of  the 
trachea. 


THE    DOG.  87 

CHAPTER  VIII. 
The  Dog. 

EVERY  one  is  familiar  with  the  great  variety  in  size, 
proportion,  fur,  and  color  presented  by  the  different 
races  of  dogs. 

We  will  not  consider  the  external  characteristics,  but 
will  study  in  the  dog  the  structure  of  the  different  regions 
of  the  body,  and  compare  this  structure  with  that  of  the 
corresponding  parts  of  our  own  organism,  noting  the 
resemblances  and  the  differences. 

_  In  examining  the  opened  trunk  we  would  find  at  once 
that  the  large  cavity  extending  from  the  base  of  the 
neck  to  the  origin  of  the  posterior  limbs  is  divided,  as  it 
is  in  ourselves,  into  two  parts,  separated  by  a  muscular 
partition  or  diaphragm. 

In  the  thoracic  cavity,  bounded  by  the  ribs,  we  would 
find  the  same  organs  that  we  know, — the  heart,  lungs, 
and  oesophagus.  In  the  abdominal  cavity  are  likewise 
lodged  the  stomach,  intestines,  liver,  spleen,  kidneys,  etc. 

There  is  nothing  specially  noteworthy  about  these 
organs,  excepting  a  greater  development  of  the  caecum, 
which  is  that  portion  of  the  large  intestine  into  which 
the  small  intestine  empties. 

The  circulatory  apparatus,  respiratory  apparatus,  and 
digestive  apparatus  are  constructed  according  to  the 
same  type  that  we  have  found  in  man.  However,  in  the 
digestive  apparatus  we  will  detect  an  important  differ- 
ence in  the  number,  form,  and  arrangement  of  the  teeth. 
In  front  the  jaws  carry  twelve  incisors,  six  above  and 


88  A    COURSE    ON    ZOOLOGY. 

six  below.  Back  of  them,  on  each  side,  and  above  and 
below,  is  a  long  conical  canine,  about  three  times  the  size 
of  the  incisors.  Still  back  of  these  are  the  large,  thick, 
and  irregular  molars,  seven  on  each  side  below,  and  six 
above,  having  great  conical  projections,  somewhat  pressed 
together  from  the  sides. 

Some  of  the  molars  have  a  single  root,  and  are  called 
premolars ;  these  are  in  front  of  the  true  molars,  which 
have  double  roots.  In  the  upper  jaw  there  are  three 
premolars  on  each  side,  while  there  are  four  in  the  lower 
jaw. 

The  prominences  that  are  noticeable  on  the  crowns  of 
the  true  molars  are  ordinarily  rounded ;  however,  the 
anterior  lower  molar  on  each  side  is  armed  with  several 
sharp  points,  and  hence  is  called  the  carnivorous  tooth. 
In  the  upper  jaw  the  last  premolar  on  each  side  is  car- 
nivorous. 

In  the  mammals  the  number  and  kind  of  teeth  in  the 
jaws  are  expressed  briefly  by  dental  formula?.  These 
formulae  are  composed  of  the  first  letter  of  the  name  of 
the  kind  of  tooth,  followed  by  a  fraction  whose  numer- 
ator is  the  figure  expressing  the  number  of  teeth  in  the 
upper  jaw,  while  the  denominator  gives  the  number  of 
corresponding  teeth  in  the  lower  jaw.  The  formulae  are 
still  further  simplified  by  expressing  the  teeth  on  only 
one  side  of  the  face,  and,  as  the  teeth  are  always  sym- 
metrically arranged,  double  the  number  given  by  the 
formulae  will  be  the  total  number  of  teeth.  Thus,  the 
formula  for  a  dog's  teeth  is 

1 1,  C  |,  Pm  |,  M  f 

The  sum  of  these  numbers  is  21 ;  there  are,  therefore 
twenty-one  teeth  on  each  side,  or  forty-two  in  all. 


THE    DOG. 


90 


A   COURSE   ON    ZOOLOGY. 


The  dog  has  an  interior  bony  framework  analogous  to 
that  which  has  been  described  in  man,  excepting  in  parts 
modified  by  the  horizontal  position  of  the  trunk  and  by 
the  quadruped  locomotion.  Thus  the  occipital  foramen, 
through  which  passes  the  spinal  marrow,  is  at  the  back 
of  the  skull.  There  are  seven  cervical  vertebrae,  as  in 
man,  and  this  number  is  uniform  in  nearly  all  mammals  ; 

FIG.  48. 


Spinal  column 


—Tail 


Scapula 
Thorax 


Radius  and  ulna 

Carpus  and 

metacarpus 

*  Digits-- 


Digits 


SKELETON  OF  DOG. 


but  there  are  thirteen  dorsal  vertebrae,  instead  of  twelve 
as  in  man,  and  consequently  the  dog  has  thirteen  pair 
of  ribs ;  there  are  seven  lumbar  vertebrae  and  three 
sacral. 

The  coccygeal  vertebrae,  which  in  man  are  joined  in 
one  littlo  mass,  have  mobile  articulations,  number  from 
eighteen  to  twenty-two,  and  form  the  framework  of  the 
tail.  Thoy  are  called  caudal  vertebrae,  In  general  among 
the  quadrupeds  the  spinal  processes  of  the  lumbar  and 
sacral  vertebrae  are  inclined  upward  from  back  to  front, 


THE    DOG. 


91 


FIG.  49. 


while  those  of  the  dorsal  vertebrsB  incline  from  front  to 
back.  In  man  and  in  the  monkeys  that  maintain  an 
erect  posture  all  the  spinal  processes  incline  from  front 
to  back. 

The  skull  of  a  dog  presents  no  striking  feature,  but  the 
face  is  very  different  from  that  of  man.  The  branches 
of  the  lower  maxillary  bone  are  proportionally  much 
elongated,  and  are  almost  straight,  while  the  articu- 
lating condyle  is  transversely  developed  in  the  form  of 
a  roller,  permitting  only  an  up-and-down  motion  of  the 
jaws,  and  no  lateral  movement  as  in  man. 

The  powerful  jaws  of  the  dog  constitute  his  only 
weapon  and  his  only  means  of  defence.  The  mouth  is 
slit  far  back,  permitting  it  to  open  very  wide ;  the  motor 
muscles  of  the  jaws 
are  very  strong;  they 
are  so  attached  to  the 
bones  as  to  afford  the 
quickest  and  the 
strongest  action. 

The  dog  is  construct- 
ed for  rapid  running, 
and  has  only  rudiment- 
ary clavicles  ;  his  paws 
and  feet  are  formed  by 
the  same  bones  as  in 
man,  and  their  position 
is  more  or  less  vertical. 
There  are  five  digits  to  the  forefeet,  the  thumb  being 
recognizable  by  its  shortness.  The  hindfeet  have  only 
four  digits.  When  the  dog  stands,  his  metacarpal  bones 
do  not  touch  the  ground ;  they  are  in  an  almost  vertical 
position,  and  the  foot  rests  on  the  phalanges.  Even  the 


B  Incisors 
A  Canines 

A  Canines 

B  Incisors 


Molars 


JAWS  AND  TEETH  OF  DOG.— The  skin  has 
been  cut  away  in  order  to  show  the 
teeth. 


92  A    COURSE    ON    ZOOLOGY. 

latter  which  carry  the  nails  or  claws  are  raised  in  such 
a  manner  that  the  claws  are  held  above  the  ground  and 
are  not  too  rapidly  worn  away. 

The  bones  of  the  limbs  are  long ;  the  muscles,  thick 
and  strong  on  the  shoulders  and  haunches,  terminate  in 
hard,  dry  tendons ;  the  articulations  are  very  flexible, 
and  allow  a  great  extension  of  the  four  limbs.  The  pos- 
sible vigor  of  projection  of  the  body  in  running  and 
jumping  is  sufficiently  indicated  by  the  great  fleshy 
development  of  the  hind-quarters. 

The  feet  are  provided  with  strong  nails  or  claws, 
slightly  curved,  and  affording  great  aid  in  climbing  steep 
and  slippery  hills.  Under  each  digit  is  a  sort  of  pad, 
rough,  strong,  and  elastic,  and  a  clover-leaf  shaped  pad 
of  the  same  nature  is  placed  under  the  palm.  By  these 
protecting  pads,  that  come  directly  in  contact  with  the 
ground,  the  digits  are  removed  from  the  ordinary  causes 
of  hurts  and  irritations.  There  is  between  the  digits  a 
fold  of  skin,  somewhat  like  the  web-foot  of  a  duck  ;  this  is 
quite  rudimentary  in  most  dogs,  but  is  largely  developed 
in  the  Newfoundland  and  the  spaniel,  and  explains  the 
great  facility  with  which  these  dogs  can  swim.  Most 
dogs  are  capable  of  swimming  for  a  long  time. 

The  body  of  the  dog  is  slender  in  the  region  of  the 
belly,  but  much  enlarged  in  the  chest,  indicating  easy 
and  deep,  respiration.  It  is  light,  relatively  to  the 
strength  of  its  limbs ;  and  because  these  latter  have  but 
a  slight  weight  to  support,  they  do  not  quickly  become 
fatigued,  and  the  animal  is  able  to  run  a  long  time 
without  losing  breath  or  requiring  rest. 

All  animals  that  hunt  game  must  have  an  accurate 
vision,  and  another  gift,  perhaps  still  more  important,  a 
delicate  sense  of  smell.  Now,  the  dog  has  excellent  sight, 


THE    DOG.  93 

and  possesses  a  sense  of  smell  superior  to  that  of  nearly 
all  other  animals.  The  faculty  of  distinguishing  odors 
resides  in  the  delicate  membrane  lining  the  interior  of 
the  nose  and  covering  certain  small  bones  contained  in 
the  nasal  fossae.  The  greater  the  surface  of  this  mem- 
brane the  more  easy  becomes  the  perception  of  odors, 
and  the  sense  of  smell  is  more  delicate  and  subtle.  The 
nose  of  the  dog  is  very  long ;  it  takes  up  two-thirds 
the  length  of  the  head,  and  contains  largely-developed 
turbinated  bones.  Besides,  the  sensitive  membrane,  which 
in  most  animals  is  limited  to  the  interior  of  the  nasal 
organ,  in  the  dog  extends  beyond  and  covers  the  fleshy 
protuberance  on  the  end  of  the  nose.  The  dog  has  thus, 
we  may  say,  two  noses, — one  internal  and  the  other  ex- 
ternal ;  the  latter  is  always  moist,  and  always  turning 
from  side  to  side  in  the  air  and  gathering  odorous  im- 
pressions. The  ears  of  the  dog  are  well  developed,  and 
in  most  cases  the  pavilion  is  much  elongated. 

All  the  organs  of  sense  are  in  direct  relation  by  con- 
necting nerves  with  the  nervous  system,  of  which  the 
general  arrangement  is  the  same  as  that  which  has  been 
described  in  man.  However,  in  the  dog  and  in  all  car- 
nivorous animals,  the  cerebrum  extends  far  beyond  the 
cerebellum,%  which  is  thus  completely  covered.  The 
olfactory  lobes  are  strikingly  developed,  being  propor- 
tional to  the  delicacy  of  the  sense  of  smell,  already 
mentioned. 

The  convolutions  are  much  more  simple  than  those  ex- 
isting in  the  brain  of  man. 

The  female  dog  nourishes  her  young  with  milk  se- 
creted by  mammary  glands  ;  these  latter  are  abdominal. 

All  races  of  dogs, — bull-dogs,  terriers,  pug-dogs,  shep- 
herd dogs,  spaniels,  beagles,  greyhounds,  setters,  pointers, 


94  A   COURSE   ON   ZOOLOGY. 

etc., — whatever  their  external  differences  of  appearance 
may  be,  have  many  points  in  common,  and  it  cannot  be 
denied  that  all  have  descended  from  a  single  primitive 
type.  This  type  is  not  known  to  us,  for  there  is  no  wild 
dog,  using  the  word  in  its  true  sense.  There  is,  indeed, 
in  the  Antilles  a  race  of  wild  dogs  living  in  an  untamed 
state,  but  they  are  descendants  of  dogs  taken  there  by 
Christopher  Columbus  and  his  followers,  and  have  be- 
come savage  by  the  absence  of  civilization  and  masters. 
It  is  worthy  of  note  that  wild  dogs  do  not  bark,  neither 
do  the  wolf  and  jackal,  both  species  being  closely  allied 
to  the  dogs ;  they  howl,  and  acquire  the  faculty  of  bark- 
ing only  after  they  have  been  domesticated. 

We  cannot  enter  into  details  concerning  the  distinctive 
characters  of  the  races  of  dogs  that  have  been  mentioned, 
saying  only  that  the  form  of  the  head  and  the  strength 
and  length  of  the  limbs  are  the  points  in  which  differences 
are  most  marked.  In  this  chapter  we  have  limited  our- 
selves to  an  anatomical  study  of  the  dog  in  general,  this 
animal  serving  as  our  type  of  quadruped. 


CHAPTER  IX. 
The  Chicken. 

IF  we  first  study  the  external  characteristics  of  the 
chicken,  we  notice  the  following  peculiarities  : 

The  animal  is  covered  with  an  epidermic  growth  called 
feathers. 

It  is  biped,  and  supports  itself  on  its  posterior  digits, 


THE    CHICKEN.  95 

while  the  forelimbs  are  profoundly  modified  to  form  new 
organs,  the  wings. 

We  have  before  us  an  animal  organized  for  flying,  and 
the  more  deeply  we  study  its  different  parts  the  more 
new  characteristics  do  we  find,  these  being  required  by 
the  new  mode  of  locomotion.  And,  first,  the  feathers  that 
cover  the  whole  surface  of  the  body  are  not  like  hairs, 
organs  only  epidermic  in  nature.  Each  feather  has  a 
•stem,  hollow  at  its  lower  end,  solid  at  its  extremity,  and 
this  stem  has  slender,  flat  beards  or  barbs,  arranged 
symmetrically  on  each  side.  The  barbs  themselves  have 
smaller  barbs,  ordinarily  hooked  at  the  ends,  holding 
themselves  firmly  fixed  one  against  the  other,  and  called 
barbules. 

The  name  down  is  given  to  the  very  light,  soft  feathers 
that  are  hidden  under  the  true  feathers ;  these  have  a 
very  slender  stem  with  many  branches,  and  possess  barbs 
without  barbules.  Consequently,  when  a  breatl*  of  air 
is  blown  upon  the  down  the  barbs  separate  one  from  the 
others,  which  cannot  take  place  in  true  feathers  whose 
hooked  barbules  hold  the  barbs  together.  In  the  eider 
duck  the  down  is  remarkably  developed  and  exceedingly 
light,  and  in  all  birds  that  inhabit  cold  countries  there 
exists  under  the  superficial  feathers  a  great  abundance 
of  down,  more  or  less  delicate,  that  is  sought  for  filling 
pillows  and  cushions. 

The  tectrices  are  feathers  that  serve  only  as  a  sort  of 
clothing  to  protect  the  body  from  cold  and  wet,  and  they 
are  covered  with  a  thin  layer  of  a  fatty  matter  that 
makes  them  quite  water-proof.  The  feathers  of  the 
upper  limbs  are  enormously  developed,  and  so  arranged 
that  they  form  the  surface  on  which  the  bird  rests  while 
flying.  They  are  called  quill-feathers,  wing-feathers,  or 


96  A    COURSE   ON    ZOOLOGY. 

remiges.  The  hand  always  has  ten,  called  primary  remi- 
ges. The  forearm  has  between  fifteen  and  twenty,  called 
secondary  remiges.  Smaller  quill-feathers  are  attached 
to  the  humerus,  and  are  named  scapularies ;  others  to 
the  thumb,  and  these  are  the  bastards.  The  coverts  of 
the  wings  are  the  feathers  that  cover  and  shield  the 
bases  or  quills  of  the  quill-feathers.  The  large  feathers 
that  form  the  tail,  and  which  are  attached  to  the  coccyx, 
are  generally  twelve  in  number,  but  sometimes  there  are 
more.  They  serve  as  a  sort  of  rudder  during  -flight,  and 
are  called  tail-feathers. 

The  superficial  examination  of  a  fowl  shows  us  also 

FIG.  50. 


WING  OF  PIGEON,  showing  primary  (a)  and  secondary  (6)  feathers,  and  "  bas- 
tard wing"  (c)  at  thumb. 

that  its  head  has  a  peculiar  form,  its  face  terminating  in 
a  horny  beak. 

In  the  interior  of  the  body,  however,  we  observe  that, 
contrary  to  what  we  have  noticed  in  the  dog,  the  tho- 
racic and  abdominal  cavities  are  not  separated  by  a  com- 


THE    CHICKEN. 


97 


plete  diaphragm ;  there  is,  however,  a  certain  indepen- 
dence of  'the  two  cavities,  and  a  certain  resemblance  to 
those  we  have  studied. 

In  the  thoracic  space  are  the  heart,  lungs,  trachea, 


FIG.  51. 


FIG.  52. 


BEAKS  OP  VARIOUS  BIRDS.— a,  marabou  stork ; 
6,  sparrow ;  c,  boatbill ;  d,  sword  bill  hum- 
ming-bird ;  e,  species  of  thrush  ;  /,  pelican ; 
g,  spoonbill ;  h,  scissorbill ;  i,  flamingo ;  .;', 
avocet ;  k,  boatbill  stork ;  I,  openbill  stork ; 
ra,  ibis ;  n,  condor ;  o,  merganser  •  p,  Columba 
cenas ;  q,  mycteria  or  saddle  stork. 


ALIMENTARY  CANAL  OF 
FOWL.— a,  oesophagus;  6, 
crop;  c,  proventriculus, 
or  secreting  stomach;  d, 
gizzard,  or  triturating 
stomach  ;  e,  intestinal  ca- 
nal; /,  two  long  caecal 
tubes  indicating  the  theo- 
retical commencement  of 
large  intestine. 


and  oesophagus,  and  in  the  lower  cavity  are  the  various 
parts  of  the  digestive  apparatus,  the  liver,  and  the 
kidneys. 

However,  the  apparatus  that  participate  in  the  vari- 
ous functions  of  nutrition  and  relation  present  marked 
E       9  9 


98 


A  COURSE  ON  ZOOLOGY. 


differences  from  the  corresponding  organs  of  man  and 
the  dog. 

The  digestive  apparatus  has  really  three  stomachs : 
1st,  the  craw,  or  first  stomach,  which  is  only  an  en- 
largement of  the  lower  end  of  the  oesophagus;  the 
food  accumulates  in  this  reservoir  so  as  to  make  it  pro- 
trude in  front  of  the  neck,  but  the  aliments  do  not  here 
undergo  any  elaboration  ;  2d,  the  succenturial  ventricle, 
or  second  stomach,  which  has  thick,  glandular  walls  that 
secrete  a  fluid  to  moisten  the  food  ;  3d,  the  gizzard,  or 
third  stomach,  formed  of  thick,  muscular  walls  lined 
interiorly  with  a  ha* d,  horny  epithelium.  The  succentu- 
rial ventricle  repre- 
sents the  stomach  of 
the  dog,  but  the  giz- 
zard is  an  apparatus 
of  trituration,  and  is 
consequently  large- 
ly developed  in  all 
graminivorous  birds. 
The  caecum  is  repre- 


FIG.  53. 


sented  by  two  tubes, 
the  terminal  orifice 
of  the  intestine  be- 
ing also  that  of  the 
urinary  ducts,  and 
forming  what  is 
called  the  cloaca. 

The      respiratory 
apparatus         differs 
sensibly    from    that 
of    the    dog.       The 
bronchi,  instead  of  being  entirely  distributed  to  the  lungs, 


LUNGS  OF  BIRD.— a,  base  of  trachea ;  6,  5,  bron- 
chial tubes ;  c,  branches  of  bronchi ;  d,  blood- 


THE   CHICKEN.  99 

are  only  partially  distributed  there.  They  are  prolonged 
to  the  orifices  of  openings  that  pass  through  the  lungs, . 
and  are  continued  beyond  them  to  large  sacs,  called 
aerial  sacs,  which  extend  into  the  abdominal  and  tho- 
racic cavities,  and  even  into  the  neck  and  along  the 
spinal  column.  These  sacs  communicate  with  the  in- 
terior of  the  bones,  which  are  hollow,  so  that  the  bird  is, 
so  to  say,  filled  with  air. 

The  circulatory  apparatus  has  nothing  specially  pecu- 
liar ;  the  blood-corpuscles  are,  however,  elliptical,  and  the 
arch  of  the  aorta,  which  turns  from  right  to  left  in  the 
dog  and  in  man,  curves  from  left  to  right  in  the  fowl. 
In  the  courses  of  the  blood-vessels  are  numerous  vascu- 
lar plexuses  in  which  circulation  is  energetic  ;  in  the  hen 
an  abdominal  plexus  furnishes  the  heat  necessary  for  the 
hatching  of  the  eggs  during  incubation.  The  exceed- 
ingly active  circulation  and  respiration  raise  the  temper- 
ature of  birds  to  108° ;  that  is  considerably  above  the 
temperature  of  mammals,  which  is  from  98°  to  100°. 

The  skeleton  of  the  chicken,  like  that  of  most  birds,  is 
peculiar  in  that  there  is  no  marrow  in  the  bones,  these 
being  hollow,  as  we  have  seen.  Besides  this  there  are 
numerous  modifications  having  for  their  object  the  pre- 
sentation of  large  surfaces  for  the  origin  and  insertion 
of  the  muscles  of  flight.  Thus,  the  sternum  has  on  the 
median  line  a  prominent  ridge  like  the  keel  of  a  ship, 
and  this  is  the  breast-bone.  This  ridge  furnishes  a"  very 
great  surface  for  the  insertion  of  the  muscles  of  the 
wing.  The  ribs  are  completely  ossified,  instead  of  having 
a  cartilaginous  extremity,  as  in  the  dog  and  in  man,  and 
each  has  towards  the  posterior  third  a  bony  prolongation 
directed  towards  the  back  and  resting  on  the  next  rib. 
These  peculiarities  have  the  effect  of  making  the  tho- 


100 


A   COURSE   ON    ZOOLOGY. 


racic  cage  stronger.  A  certain  number  of  the  lumbar 
and  sacral  vertebrae  are  firmly  united  together. 

There  are  fourteen  cervical  vertebrae,  all  long  and  very 
mobile,  and  seven  dorsal  vertebrae. 

The  skull  is  well  developed,  and  its  bones  are  united  in 


Pelvis 
Coccyx 


Beak 


Spinal  column 


Breast-bone 

Thigh 

Sternum 


Toes 


SKELETON  OF  CHICKEN. 

a  single  compact  mass.     It  is  articulated  with  the  verte- 
bral column  by  a  single  condyle. 

The  forelimbs  are  only  supports  for  the  feathers  which 
serve  in  flight.  The  hand  is  only  a  sort  of  stump,  com- 
monly called  the  pinion.  The  shoulder,  besides  the  clav- 
icles, properly  speaking,  which  are  united  together  in 
front,  forming  the  "  wish-bone,"  has  a  well-developed  sup- 
port in  the  coracoid  process  of  the  scapula,  which  forms 


THE    CHICKEN.  '*•»*  ''  ''*   i     V    101 


a  flying  arch  extending  entirely  to 
posterior  limbs  are  made  up  of  a  short,  strong  thigh,  a 
leg,  and  a  tarsus,  corresponding  at  the  same  time  to  the 
tarsus  and  metatarsus,  and  digits  ordinarily  four  in  num- 
ber. The  much-elongated  metatarsus  constitutes  what  is 
ordinarily  called  the  leg  of  the  fowl.  The  number  of 
phalanges  follows  a  rule  that  is  constant  for  birds.  The 
first  digit  has  two  phalanges,  the  second  has  three,  the 
third  four,  and  the  fourth  five.  Besides  these,  the  cock 
has  a  spur,  which  is  a  sort  of  bony  prolongation  of  the 
metatarsus,  and  must  not  be  mistaken  for  a  digit. 

The  nervous  system  comprises  the  same  parts  as  in 
the  dog,  but  these  are  modified  to  some  extent.  The 
convolutions  of  the  cerebrum  are  almost  wanting ;  the 
cerebellum,  instead  of  being  formed  of  largely-developed 
lateral  lobes  with  a  thin  median 
lobe,  has  a  large  median  lobe  FIG.  55. 

and  very  small  lateral  lobes. 
Lastly,  there  is  no  corpus  cal- 
losum. 

The  organs  of  sense  are  for 
the  most  part  well  developed. 
However,  the  tongue  is  re- 
duced to  a  pointed,  horny,  and 
very  thin  appendage ;  this  leads 
us  to  the  conclusion  that  the 
sense  of  taste  is  very  feeble.  EYE  OP  BIRD. 

The  eye  is  very  large  in  pro- 
portion to  the  size  of  the  head,  and  is  in  all  birds  pro- 
tected by  three  eyelids,  two  horizontal  and  one  vertical ; 
the  latter  comes  from  the  internal  angle  of  the  eye,  and 
is  called  the  nictating  membrane.  The  iris  is  large  and 
pierced  by  a  round  pupil.  A  black  membrane,  folded 

9* 


102 


A   COURSE   ON  ZOOLOGY. 


FlQ.  56. 


.  "-If fie- 'a*fan,"ahS  'called  the  comb,  starts  from  the  retina 
and  proceeds  towards  the  interior  of  the  crystalline  lens. 
The  power  of  vision  is  very  acute  in  birds.  They  can 
perceive  their  prey,  however  small  it  may  be,  at  enor- 
mous distances. 

The  narines  are  situated  at  the  base  of  the  beak,  and 
the  sense  of  smell  appears  to  be  feebly  developed. 
The  ears  are  well  formed,  but  have  no  pavilions. 
The  chicken,  like  all  crowing  and  singing  birds,  has 
two  larynxes,  of  which  the  one  situated  at  the  upper 
end  of  the  trachea  corresponds  to  the  larynx  of  mam- 
mals,   but    is    without    vocal    cords, 
while  the   lower   one,  placed   at   the 
lower  end  of  the  trachea,  at  the  bi- 
furcation of  the   bronchus,    is    more 
particularly    adapted    for    the    pro- 
duction of  the  voice.      This  explains 
why  a  barn-yard  fowl  often  continues 
to  produce  sounds  even  .after  its  head 
is  cut  off.     The  lower  larynx  is  called 
the  sing-box  or  syrinx. 

All  birds  are  oviparous, — that  is, 
they  reproduce  the  species  by  eggs, 
and  have  no  organs  designed  for  nour- 
ishing their  young. 

The  egg  of  the  chicken  will  give  us 
an  excellent  idea  of  the  structure  of 
the  eggs  of  all  birds.      The  external 
envelope,  or  shell,  consists  of  a  calca- 
reous crust,  very  porous,  and  lined  in- 
ternally with  a  thin  double  membrane, 
called  the  chorion,     Inside  of  this  is  a  viscous,  transparent 
liquid,  coagulable  by  heat ;  this  is  the  white  of  egg,  or  albu- 


d 


SYRINX  OF  THRUSH.— 
a,  trachea  (opened 
below) ;  6,  bronchi 
(with  rings);  c,  in- 
ternal tympaniform 
membrane ;  d,  mus- 
cles ;  e,  nerve  supply- 
ing muscles. 


THE    CHICKEN. 


103 


men.  In  the  centre  is  a  yellow,  spherical  mass,  the  vitellus 
or  yolk,  fixed  in  its  position  by  very  delicate  ligaments 
composed  of  the  albumen  twisted  on  itself.  The  vitellus 
is  formed  of  an  agglomeration  of  very  small  vesicles  en- 
veloped by  an  exceedingly  thin  pellicle.  Upon  one  point 
of  its  surface  is  found  a  whitish  rounded  spot ;  this  is  the 
cicatricle,  or  germ  of  the  young  bird.  During  incubation 
this  germ  develops,  becomes  organized,  and  absorbs  for 
its  own  nutrition  all 
the  matter  contained  IQ' 

in  the  egg.  The 
white  and  the  yolk 
are  only  magazines 
of  nourishment.  In 
the  egg  of  the 
chicken  these  two 
substances  exist  in 
about  equal  propor- 
tions. The  white  is 
composed  of  thir- 
teen per  cent,  of  a 
nitrogenized  matter, 
named  albumen,  and 
eighty-seven  per  cent,  of  water.  The  yolk  contains  nine- 
teen per  cent,  of  a  nitrogenous  matter,  called  vitelline, 
twenty-nine  per  cent,  of  a  fatty  matter,  called  egg-oil, 
and  fifty-one  per  cent,  of  water,  with  a  small  quantity 
of  a  sulphurized  matter.  The  decomposition  of  this 
matter  produces  hydrogen  sulphide,  which  gives  the 
characteristic  unpleasant  odor  to  rotten  eggs. 

In  the  egg  the  bird  finds  nitrogenized  and  fatty  mat- 
ters,— that  is,  all  the  elements  necessary  for  its  develop- 
ment and  the  formation  of  its  tissues, — and  the  shell 


SECTION  OF  FOWL'S  EGG.— a,  central  plug  of 
white  yolk ;  6,  position  of  germinal  area ;  c, 
yellow  yolk ;  d,  white  of  egg ;  e,  "  tread"  or 
chalaza;  /,  air-space  between  outer  mem- 
branes. 


104  A    COURSE    ON    ZOOLOGY. 

furnishes  the  rudimentary  substance  for  the  mineral  mat- 
ter of  the  bones.  The  air  which  must  be  supplied  for 
the  respiration  of  the  embryo  passes  through  the  pores 
of  the  shell,  and  there  is  at  the  large  end  of  the  egg  a 
sort  of  reservoir,  the  air-chamber,  contained  between  the 
two  layers  of  the  chorion.  Air  is  indispensable  for  the 
development  of  the  germ.  When  eggs  are  to  be  pre- 
served for  food  they  are  dipped  in  a  solution  of  lime  or 
some  other  substance  that  will  close  up  the  pores  of  the 
shell. 

The  constituent  parts  of  the  egg  are  not  all  formed  in 
the  same  organs.  The  yolk  or  vitellus  is  organized  in 
the  ovaries,  which  form  a  bunch  suspended  from  the 
posterior  walls  of  the  abdomen  of  the  bird.  When  de- 
tached from  the  ovary,  the  yolk  descends  towards  the 
cloaca  through  a  canal  called  the  oviduct;  here  it  be- 
comes covered  with  the  albumen,  and  as  the  yolk  has  in 
its  descent  a  motion  of  rotation  on  its  axis,  there  results 
a  torsion  that  forms  the  albuminous  ligament.  In  the 
lower  parts  of  the  oviduct  are  secreted  the  calcareous 
matter  of  the  shell  and  the  coloring  substances  that  in 
certain  species  tint  the  surface.  The  egg  is  then  passed 
into  the  cloaca  and  is  expelled. 

In  order  that  the  egg  may  be  hatched  it  must  for 
a  certain  length  of  time  be  maintained  at  a  temperature 
of  about  107°,  and  for  this  reason  the  mother  sits  on  it. 

In  the  domestic  state  the  cock  does  not  help  the  hen 
either  in  the  cares  of  incubation  or  in  the  rearing  of  the 
young  family,  but  he  intrepidly  defends  his  hens  and 
chicks  from  all  attacks  and  dangers. 


THE    LIZARD. 


105 


CHAPTER  X. 
The  Lizard  and  the  Prog. 

The  Lizard. — Lizards  are  small  terrestrial  reptiles, 
most  of  them  perfectly  inoffensive,  found  in  great  abun- 
dance in  the  warm  and  even  the  temperate  parts  of  both 
continents.  They  live  on  worms  and  insects,  and  so  de- 
stroy large  numbers  of  creatures  annoying  to  man.  There 
are  several  species  of  lizard, — the  gray,  green-spotted, 

FIG.  58. 


COMMON  LIZARD  (Lacerta  vivipara). 

brown,  and  red.  The  common  lizards  of  temperate 
countries  are  rarely  longer  than  six  or  eight  inches. 
They  usually  prefer  to  live  inj*ocky  places  or  walls  ex- 
posed to  the  sun.  The  tail  is  made  up  of  articulations 
that  are  broken  off  with  great  ease,  but  the  lost  part  is 
afterwards  reproduced.  The  colors  of  many  of  the 


106  A    COURSE   ON    ZOOLOGY. 

species  are  very  brilliant,  and  the  length  of  those  found 
in  warm  climates  may  exceed  sixteen  or  twenty  inches  ; 
in  such  countries  they  live  in  hedges  and  bushes. 

The  common  lizard  may  be  taken  as  a  type  for  the 
study  of  the  organization  of  all  reptiles.  It  has  four  feet, 
supporting  a  long,  slender  body,  terminated  by  a  long 
tail,  and  is  covered  with  a  scaly,  naked  skin  that  bears 
neither  hair  nor  feathers.  At  a  certain  season  of  the 
year  the  lizard  gets  a  new  skin,  and  throws  off  the  old 
epidermis. 

On  dissecting  the  lizard  we  find  that  there  is  no  divi- 
sion between  the  thoracic  and  abdominal  cavities  :  there 
is  no  real  diaphragm.  The  digestive  apparatus  is  simple, 
and  after  the  mouth,  which  is  armed  with  short  teeth,  we 
find  a  straight  oesophagus,  a  stomach,  and  an  intestine, 
ending  in  a  cloaca,  as  in  the  birds. 

The  circulatory  apparatus  differs  from  those  which  we 
have  already  studied :  there  are  but  three  cavities  in  the 
heart,  two  auricles  and  one  ventricle.  In  this  ventricle 
the  arterial  and  venous  blood  are  mixed,  so  that  the  cir- 
culation, instead  of  being  complete,  as  in  mammals  and 
in  birds,  is  incomplete, — that  is,  there  is  a  mixture  of  the 
two  kinds  of  blood. 

The  blood-corpuscles  are  elliptical,  like  those  of  birds, 
but  they  are  much  larger,  and  have  a  distinct  nucleus. 

There  are  two  aortic  arches,  one  right  and  one  left, 
which  unite  back  of  the  heart  to  form  a  single  vessel. 

The  respiratory  function  is  accomplished  by  lungs,  but 
these  are  much  less  developed  than  in  the  animals  we 
have  studied.  ^ 

The  skeleton  is  not  unlike  those  we  have  examined. 
The  skull  is  flat  and  depressed.  The  vertebrae  are  con- 
cavo  convex, — that  is,  at  the  posterior  extremity  they 


THE    LIZARD. 


107 


are  convex,  while  at  the 
.forepart  they  are  con- 
cave. Each  of  the  four 
limbs  is  terminated  by 
five  digits. 

The  organs  of  sense 
are  much  like  those  of 
the  bird.  The  tongue 
is  forked.  The  eyes  are 
furnished  with  a  nicta- 
ting membrane  or  third 
eyelid.  The  ears  have 
no  pavilion  and  no  ex- 
ternal meatus,  so  that 
the  tympanum  is  on  a 
level  with  the  skin. 

The  olfactory  lobes 
are  placed  in  front  of 
the  cerebral  hemi- 
spheres, and  these  lat- 
ter are  separated  from 
the  cerebellum  by  the 
optic  thalami.  In  brief, 
those  parts  of  the  brain 
that  in  mammals  and 
birds  are  massed  to- 
gether are  in  the  lizard 
spread  out  and  grouped 
in  linear  series,  the  ones 
behind  the  others. 

Like  all  other  animals 
of  the  class  of  reptiles, 
and  like  birds,  the  lizard 


108  A   COURSE   ON   ZOOLOGY. 

reproduces  its  species  by  eggs ;  but  the  mother  does  not 
sit  on  the  eggs;  they  are  laid  in  places  which  are  most, 
likely  to  be  favorable  for  the  hatching. 

From  what  has  already  been  said  of  the  mixture  of 
venous  and  arterial  blood,  the  conclusion  can  easily  be 
drawn  that  the  blood  that  circulates  in  the  lizard  is  not 
pure.  Hence  there  is  a  less  activity  in  the  respiratory 
combustion,  since  the  blood  is  less  charged  with  oxygen  ; 
consequently  the  temperature  of  the  animal  is  lower,  and 
reptiles  are  called  cold-blooded  animals,  in  comparison 
with  birds  and  mammals,  which  are  spoken  of  as  warm- 
blooded animals.  These  terms  must  not  be  interpreted 
literally.  It  would  be  more  exact  to  say  that  reptiles 
have  a  variable  temperature, — that  is,  the  temperature  is 
about  that  of  surrounding  objects,  while  birds  and  mam- 
mals are  animals  of  constant  temperature.  When  it  is 
cold,  the  latter  are  able  to  increase  the  respiratory  com- 
bustion and  to  maintain  the  bodily  heat ;  while,  when 
the  weather  is  warm,  a  more  restricted  diet  and  less 
active  movement  are  followed  by  a  diminished  combus- 
tion, and  consequently  the  high  external  temperature 
meets  an  internal  balance.  Lizards,  and  in  general  all 
reptiles,  have  no  power  to  maintain  such  equilibrium  of 
temperature. 

The  Frog, — The  frog  belongs  to  the  class  of  batra- 
chians.  It  has  a  naked,  clammy  skin,  covered  with  a 
thin  epithelial  layer,  which  is  continually  being  renewed. 
It  has  two  pair  of  feet  and  has  no  tail. 

The  thoracic  and  abdominal  cavities  are  not  separated 
by  a  diaphragm.  The  digestive  apparatus  is  not  unlike 
that  of  the  lizard  ;  the  jaws  are  provided  with  small 
teeth. 

In  the  respiratory  apparatus,  the  lungs  are  only  two 


THE    FROG. 


109 


sacs   opening    directly  into    the    larynx;    there    is    no 
trachea. 

FIG.  60. 


FROG  OPENED  FROM  BELOW.— E,  stomach ;  C,  heart ;  c,  aortic  arches  ;  P,  lungs ; 
F,  liver ;  R,  kidneys ;  I,  large  intestine ;  V,  bladder ;  i,  small  intestine ;  ov, 
ovary ;  od,  oviducts ;  I,  tongue,  turned  to  one  side  together  with  lower  jaw. 


The  heart  has  three  cavities,  two   auricles  and  one 
ventricle,  so  that  circulation  is  incomplete,  as  in  reptiles. 

10 


110 


A   COURSE   ON   ZOOLOGY. 


There  are  two  aortic  arches,  springing  from  a  dilatation 
or  aortic  bulb. 

The  skeleton  is  remarkable  by  the  shortness  of  the 

vertebral  column, 

FIG.  61.  which     has    only 

eight  vertebrae. 
There  are  neither 
sternum  nor  ribs, 
and  consequently 
there  is  no  tho- 
racic cage ;  the 
frog  is  therefore 
unable  in  respira- 
tion to  make  move- 
ments of  inhala- 
tion and  exhala- 
tion, such  as  we 
have  studied  in 

the  animals  already  considered;  it  swallows  the  air 
by  deglutition,  as  we  would  swallow  a  mouthful  of 
food. 

The  brain  of  the  frog  has  two  elongated  cerebral 
hemispheres,  two  large  optic  thalami  behind  the  hemi- 
spheres, and  a  cerebellum  consisting  only  of  a  transverse 
nerve  band  close  to  the  optic  thalami. 

The  organs  of  sense  are  well  developed.  The  eye  has 
a  nictating  membrane ;  the  ear  has  neither  pavilion  nor 
external  canal,  and  its  tympanum,  like  that  of  the  lizard, 
is  on  a  level  with  the  skin. 

The  organization  of  frogs  corresponds  to  their  man- 
ner of  life.  Like  toads  and  aquatic  salamanders  they 
can  live  under  water  as  do  fishes,  and  they  possess  a 
power  entirely  absent  in  fish, — to  live  quite  as  well  in 


SKELETON  OF  FROG. 


THE    FROG. 


Ill 


the  air.     Animals  thus  gifted  with  what  really  constitute 
two  modes  of  life  are  said  to  be  amphibious. 

We  must  understand  the  meaning  of  this  word  am- 
phibious. An  accomplished  diver  can  spend  quite  an 
interval  of  time  under  water.  The  otter,  the  seal,  and 
some  other  animals  can  re- 
main submerged  several  min- 
utes without  inconvenience. 
However,  neither  the  diver, 
the  seal,  nor  the  otter  is  an 
amphibian ;  while  they  can 
remain  a  short  time  under 
water,  they  cannot  do  so  in- 
definitely. While  they  are 
submerged,  pulmonary  res- 
piration is  completely  sus- 
pended, and  their  stay  under 
water  cannot  be  prolonged 
beyond  the  time,  always  very 
limited,  in  which  arrested 
respiration  is  followed  by 
death. 

It  is  not  so  with  true  am- 
phibians. If  a  frog  be  placed 
in  a  vessel  full  of  water  and 
kept  at  the  bottom  so  that 
it  cannot  possibly  come  to 
the  surface,  it  will  neverthe- 
less continue  to  live  indefinitely  without  appearance  of 
discomfort  as  long  as  it  is  furnished  with  food,  provided 
the  water  be  aerated  or  frequently  changed.  It  lives 
under  water  as  naturally  and  as  easily  as  a  fish  ;  it  also 
lives  in  air  as  comfortably  as  do  terrestrial  animals :  it  is 


ARTERIAL  SYSTEM  OF  AMPHIBIAN. 
— ra,  right  auricle ;  la,  left  auri- 
cle ;  v,  ventricle ;  ca,  conus  arte- 
riosus ;  c,  carotid  arteries ;  aa, 
aortic  arches ;  ao,  dorsal  aorta ; 
pa,  pulmonary  artery ;  pv,  pul- 
monary vein ;  ra,  receives  ve- 
nous blood  from  body ;  both  the 
pulmonary  arteries  enter  la. 
(After  Nuhn.) 


112  A   COURSE   ON   ZOOLOGY. 

truly  amphibious.  In  order  thus  to  live  in  water  like  a 
fish,  the  frog,  the  toad,  and  the  salamander  must  possess 
respiratory  organs  adapted  to  aquatic  life ;  and  in  order  to 
live  in  the  air  like  man,  the  dog,  or  the  lizard,  they  must 
also  possess  the  organs  necessary  for  aerial  respiration. 

The  frog,  the  toad,  and  the  salamander  have  indeed 
lungs.  We  can  satisfy  ourselves  on  this  point  by  watch- 
ing them  for  a  moment,  when  we  will  observe  the  move- 
ments of  swallowing,  by  which  they  replace  the  respira- 
tory movements,  as  we  have  already  seen.  But  we  would 
seek  in  vain  in  these  animals  any  respiratory  organs 
adapted  for  aquatic  life,  such  as  we  find  in  the  fish. 

The  aquatic  respiration  of  the  frog  is  not  effected  by 
any  special  organ :  it  takes  place  over  the  entire  surface 
of  the  skin.  The  latter  is  thin,  always  moist,  very  porous 
to  the  air,  and  the  blood  which  circulates  under  it  comes 
into  almost  immediate  contact  with  the  atmosphere. 
The  cutaneous  respiration  is  thus  so  active  that  it  is  able 
to  maintain  the  life  of  the  animal  under  water.  Frogs 
from  which  the  lungs  had  been  entirely  removed  have 
continued  to  live  several  months  under  water  by  cuta- 
neous respiration  only,  while  others,  whose  skin  had 
been  covered  with  an  impermeable  varnish,  preventing 
entirely  the  passage  of  air,  soon  died,  and  apparently  of 
suffocation.  If  the  skin  of  a  frog  be  dried,  the  animal 
quickly  dies,  because  the  drying  prevents  the  passage  of 
air  to  the  blood  beneath.  These  facts  explain  why  am- 
phibians always  select  for  their  abodes  cool  and  moist 
places,  such  as  the  banks  of  streams  and  ponds. 

An  important  peculiarity  of  frogs  and  other  animals 
of  the  same  group  is  the  metamorphosis  that  accompanies 
their  development.  The  eggs  are  laid  in  considerable 
numbers  in  marshes  and  ponds,  and  are  agglutinated 


THE    FROG. 


113 


by  a  colorless,  mucilaginous  substance.  Now,  if  we 
watch  the  development  of  these  eggs  we  find  that  they 
give  birth,  not  to  frogs,  but  to  small  beings  known  as 
tadpoles,  organized,  like  fishes,  for  an  entirely  aquatic 
life.  An  elongated  ball  containing  the  head  and  body ; 
a  long  tail,  flattened  on  the  sides ;  neither  limbs  nor 
fins ;  external  respiratory  apparatus,  consisting  of  little 
bags  or  branchiae  on  each  side  of  the  head ;  a  mouth 
adapted  only  for  vegetable  food  :  such  is  the  general 
appearance  of  an  amphibian  in  the  tadpole  state.  The 
animal  retains  this  form  during  a  longer  or  shorter  time, 

FIG.  63. 


METAMORPHOSES  OP  THE  FROG.— A,  frog's  eggs;  B,  tadpole,  first  without  feet; 
C,  the  two  hindfeet  appear ;  D,  the  two  forefeet  appear ;  E,  the  animal  has 
four  feet  and  a  tail ;  F,  the  tail  disappears,— the  animal  is  perfect. 

according  to  the  species,  and  depending  on  external  con- 
ditions. Then  the  limbs  begin  to  appear  and  become 
developed ;  the  form  changes ;  the  head  becomes  out- 
lined ;  the  tail  either  disappears  entirely,  as  in  frogs  and 
toads,  or  remains,  as  in  the  salamander ;  the  branchiae 
shrink  away  and  are  obliterated,  and  the  lungs  develop. 
Now  the  animal  begins  to  seek  the  air ;  it  nourishes  itself 
by  preference  on  worms,  insects,  and  little  mollusks.  It 
abandons  the  water  as  its  constant  home ;  sometimes,  as 
in  the  toad,  it  gives  up  aquatic  life  entirely,  selecting  as 
its  abode  a  damp  hole  in  an  old  wall  or  a  cool  place  under 
stones,  and  only  returning  to  the  water  in  order  to  de- 
h  10* 


114  A   COURSE   ON   ZOOLOGY. 

posit  its  eggs,  impelled  by  that  instinct  of  necessity  that 
makes  known  to  all  animals  the  conditions  most  favor- 
able for  the  preservation  of  their  young,  and  consequently 
of  their  species. 

Frogs  live  on  the  borders  of  water  and  feed  on  in- 
sects and  worms,  and  during  cold  weather  they  bury 
themselves  in  the  mud  of  marshes.  The  green  frog  is 
common  in  ponds,  and  is  sought  after  as  food  in  many 
countries.  Brown  frogs  and  toads  prefer  gardens,  where 
they  render  great  service  by  destroying  snails  and  de- 
structive insects.  The  little  green  tree-frogs  have  suck- 
ers in  the  ends  of  their  digits,  by  the  aid  of  which  they 
can  climb  trees  and  crawl  from  branch  to  branch  in  search 
of  the  insects  on  which  they  live. 

In  conclusion,  we  must  lay  stress  on  the  importance  in 
classification  of  the  metamorphosis  of  the  frog.  The 
organization  of  the  tadpole,  absolutely  that  adapted  to 
aquatic  life,  relates  the  amphibians  to  the  fishes,  while  by 
the  organization  of  the  adult  animals  they  are  related  to 
other  terrestrial  animals.  The  amphibians  thus  form  a 
natural  passage  from  the  study  of  terrestrial  animals  to 
that  of  fishes. 


CHAPTER  XI. 
The  Carp. 

THE  carp  belongs  to  the  class  of  fishes,  and  we  will  study 
it  as  the  type  of  this  category  of  animals.  An  exami- 
nation of  its  external  character  shows  us  at  once  that 
there  are  great  modifications  that  distinguish  it  from 
all  that  we  have  so  far  studied.  Its  organization,  like 


THE   CARP.  115 

that  of  all  fishes,  is  adapted  for  an  entirely  aquatic  ex- 
istence. 

The  profile  of  the  carp  presents  a  wide  body,  flattened 
at  the  sides,  the  back  more  or  less  arched  in  front  and 
dropping  towards  the  head,  which  is  short,  having  a 
small  mouth,  with  two  fleshy  processes,  called  barbels,  at 
each  side. 

The  body  is  not  naked,  as  in  the  frog  ;  it  is  covered  not 
with  hair  nor  feathers,  but  with  little  organs,  called  scales, 
which  are  arranged  in  longitudinal  rows  ;  from  the  head 
to  the  tail  each  row  contains  about  thirty-six  or  thirty- 

FIG.  64. 


CARP  (Gyprinus  carpio).—a,  pectoral  fin;  6,  ventral  fin;  c,  anal  fin;  d,  large 
barbel ;  e,  dorsal  fin. 

eight  scales,  and  there  are  about  a  dozen  rows,  separated 
into  two  nearly  equal  groups  by  a  line  that  is  apparent 
in  all  fish,  and  known  as  the  lateral  line. 

The  carp,  being  organized  for  life  under  water,  does 
not  possess — like  the  animals  already  studied — long  and 
slender  limbs.  It  has  a  special  motor  apparatus  that 
is  common,  with  more  or  less  modifications,  to  all 
fishes. 

This  apparatus  is  composed  of  two  kinds  of  organs, 
known  as  fins ;  some  of  these  are  arranged  on  the  sides 


116  A   COURSE   ON    ZOOLOGY. 

of  the  body,  and  represent  the  limbs ;  the  others  are  in 
the  median  line,  and  are  more  or  less  directly  connected 
with  the  spinal  column.  In  the  first  of  these  varieties 
of  fins  are  found,  greatly  modified  it  is  true,  the  bones 
that  form  the  limbs  of  mammals.  The  median  fins  are 
supported  by  little  rods  or  rays  of  a  bony  nature. 

The  fins  that  correspond  to  the  upper  limbs  are  called 
pectoral  fins.  They  are  absent  in  but  a  small  number 
of  fishes ;  they  are  usually  in  pairs,  nearly  always  in- 
dependent of  each  other,  and  are  situated  near  the 
gills. 

The  fins  corresponding  to  the  lower  limbs  are  named 
ventral  fins  ;  they  are  absent  in  some  fishes,  among  which 
is  the  eel,  and  in  those  in  which  they  exist  they  are 
placed  either  under  the  throat,  as  in  the  codfish  and 
whiting,  below  the  pectoral  fins,  as  in  the  perch  and 
mullet,  or  under  the  abdomen.  The  latter  is  the  case 
in  the  carp,  in  which  these  fins  have  ten  or  eleven 
rays. 

Of  the  median  fins  the  most  noticeable  is  the  dorsal, 
which  is  missing  in  some  fishes,  and  presents  great  modifi- 
cation in  form  and  number  in  the  different  species.  The 
carp  has  one  large  dorsal  fin,  of  which  the  first  ray  is 
strong  and  notched  like  a  saw,  and  succeeded  by  eighteen 
or  twenty  others  that  support  the  fin. 

At  the  extremity  of  the  vertebral  column  a  terminal 
forked  fin  constitutes  the  tail  of  the  fish.  Lastly,  near 
the  anus,  and  always  in  the  median  line,  is  the  anal  fin, 
the  anterior  ray  of  which  is  saw-toothed. 

Fish  swim  in  water  as  birds  fly  in  the  air, — that  is, 
they  exert,  by  the  aid  of  their  organs  of  locomotion,  a 
pressure  upon  the  fluid  that  surrounds  them  sufficient  to 
enable  them  to  offer  firm  resistance.  The  posterior  por- 


THE   CARP.  117 

tion  of  the  body  acts  as  a  sort  of  oar,  whose  rapid  mo- 
tions play  the  principal  part  in  progression.  The  actions 
of  the  median  fins  and  of  the  tail  are  combined  to  deter- 
mine the  direction  of  the  motion.  The  lateral  fins  appear 
to  have  their  most  important  function  in  maintaining 
equilibrium. 

If  we  open  a  carp  in  order  to  examine  its  internal 
structure,  we  find  before  us  an  organization  quite  dif- 
ferent from  anything  we  have  observed  in  the  animals 
already  studied. 

At  first  we  notice  that  a  large  portion  of  the  abdomen 
is  filled  with  a  capacious  bladder,  tightly  contracted  in 
the  middle,  and  communicating  with  the  oesophagus  by 
a  long  canal.  This  is  the  swimming-bladder,  which  exists 
in  a  large  number  of  the  species  of  fishes,  and  contributes 
in  an  efficacious  manner  to  simplify  the  mechanism  of 
locomotion.  This  bladder  is  filled  or  emptied  of  air  at 
the  will  of  the  fish,  so  that  the  body,  being  decreased  or 
increased  in  density,  rises  or  sinks  in  the  water  without 
any  effort  of  the  fins.  The  gas  in  the  swimming-bladder 
does  not  come  from  the  exterior :  it  is  secreted  by  the 
walls  of  the  membrane.  There  is  no  swimming-bladder 
in  those  species  that  constantly  remain  at  the  bottom 
of  the  water  near  the  mud  in  which  they  seek  their 
food. 

The  digestive  apparatus  also  occupies  a  considerable 
portion  of  the  abdominal  space.  The  intestinal  canal  of 
the  carp,  indicating  an  essentially  vegetable  diet,  is  long, 
folded,  and  partly  hidden  among  the  numerous  lobes  of 
the  liver.  The  mouth  has  no  teeth  in  its  jaws ;  the  palate 
is  thick  and  fleshy ;  the  tongue  is  largely  developed,  as 
it  is  indeed  in  all  fishes. 

The  respiratory  apparatus  presents  important  peculi- 


118 


A    COURSE   ON    ZOOLOGY. 


arities,  due  to  the  aquatic  life.  Like  all  animals,  fishes 
require  air  in  order  to  live,  and  they  find  this  air  in 
the  water;  their  organs  for  renewing  the  air  are  so 
constituted  that  they  can  only  function  usefully  in 
water. 

It  can  easily  be  shown  that  water  contains  dissolved 
air.  This  air  separates  and  collects  in  little  bubbles  on 
the  walls  of  a  glass  in  which  water  is  allowed  to  stand 

FIG.  65. 


HEAD  OF  CARP  WITH  THE  GILL-COVER  REMOVED.— 6,  barbels ;  i,  iris ;  p,  pupil ; 
a,  branchial  arches,  having  the  comb-like  teeth,  d,  on  the  internal  border ; 
r,  rays  of  the  gills. 

and  become  warm.  If  water  be  boiled  in  a  glass  vessel 
the  bubbles  may  be  seen  to  rise  and  escape  at  the  surface, 
and  with  the  proper  apparatus  the  gas  may  be  collected 
and  its  chemical  composition  determined.  It  is  then 
found  to  be  air.  This  air  is  expelled  from  the  water  by 
the  elevation  of  temperature,  and  all  the  air  may  be  thus 


THE    CARP. 


119 


120  A  COURSE  ON  ZOOLOGY. 

driven  out.  When  this  happens  the  water  is  no  longer 
able  to  sustain  the  life  of  fish,  and  the  experiment  is  easy 
to  perform.  It  must  not  be  forgotten,  however,  that 
water  dissolves  a  certain  quantity  of  air  with  great  ease, 
and  that  when  the  dissolved  air  has  been  expelled  by 
boiling  it  is  soon  absorbed  again  when  the  water  is  ex- 
posed to  the  air. 

The  respiratory  organs  of  fishes  are  located  at  the 
back  and  sides  of  the  mouth,  in  a  cavity  that  communi- 
cates with  the  exterior  by  two  lateral  openings,  called 
the  gill-openings.  These  organs,  called  the  gills  or 
branchiae,  are  generally  composed  of  plates  arranged  like 
the  teeth  of  a  comb  upon  four  pair  of  bony  arches,  called 
the  branchial  arches,  They  are  directly  under  the  bony 
plates  that  form  the  cheeks  of  the  fish,  and  that  attain 
a  great  development  and  are  very  distinctly  striated  in 
the  carp.  These  are  the  opercula  or  gill-covers,  and 
when  they  are  raised  the  gill-openings  gape  behind  them. 

Certain  rays,  three  only  in  number  in  the  carp,  sup- 
port a  membrane  which  closes  the  respiratory  cavity 
below  and  at  the  sides. 

The  branchial  plates  receive  innumerable  little  blood- 
vessels; the  water  which  is  drawn  in  at  the  mouth 
comes  in  contact  with  these  respiratory  organs,  yielding 
to  the  blood  through  the  thin  membrane  separating  the 
two  liquids  a  part  of  the  oxygen  it  holds  in  solution, 
and  taking  in  exchange  carbonic  acid  gas  that  must 
be  removed.  After  having  served  its  purpose  for  res- 
piration the  water  is  then  expelled  through  the  gill- 
openings. 

Fishes  thus  respire  in  reality  like  other  vertebrates, — 
that  is,  they  absorb  oxygen  and  eliminate  carbonic  acid, 
but  their  respiratory  organs  are  so  constituted  that  they 


THE    CARP.  121 

can  act  efficaciously  only  under  water,  although  that 
liquid  contains  but  a  small  proportion  of  air  in  solution. 
Fish  die  in  the  air  because  the  branchial  plates,  no  longer 
floating  and  separated  by  the  water,  stick  together  and 
present  but  a  small  surface  to  the  air. 

In  the  circulatory  apparatus  the  heart  has  only  two 
cavities,  one  auricle  and  one  ventricle.  It  is  a  venous 
heart,  and  represents  the  right  heart  of  the  mammals. 
The  venous  blood  arrives  from  the  body  to  the  interior 
of  the  auricle,  passes  hence  to  the  ventricle,  and  is  then 
propelled  to  the  respiratory  apparatus.  This  is  the 

FIQ.  67. 


SKELETON  OF  A  FISH. 

function  of  the  right  heart  in  mammals.  From  the 
gills,  however,  instead  of  returning  to  a  left  heart,  the 
blood  is  at  once  distributed  over  the  system  ;  there  is  but 
one  circuit,  and  the  circulation  is  said  to  be  single,  in- 
stead of  double  as  in  the  other  vertebrates.  It  is  a  com- 
plete circulation,  for  there  is  no  mixture  of  venous  and 
arterial  blood.  We  may  add  that  the  ventricle  is  followed 
by  a  sort  of  swelling  or  aortic  bulb. 

The  skeleton  of  the  carp,  like  that  of  other  fishes,  is 
constructed  according  to  the  general  plan  of  the  vertebral 
F  11 


122  A    COURSE    ON    ZOOLOGY. 

organization,  but  its  parts  are  naturally  modified  to  suit 
the  special  conditions  of  the  medium  in  which  fishes  live. 
The  bones  that  form  the  head  are  very  numerous,  but 
those  of  the  limbs  are  never  present  except  in  a  rudi- 
mentary condition,  and  the  posterior  limbs  are  often  ab- 
sent. In  some  species  the  ribs  also  are  missing,  while  in 
compensation  the  existence  of  the  median  fins  necessitates 
the  presence  of  a  large  number  of  supplementary  carti- 
lages or  bones  for  their  support.  On  the  other  hand, 
though  the  bones  of  most  species  of  fish  have  a  chemical 
composition  analogous  to  that  of  the  bones  of  mammals, 
birds,  and  reptiles,  yet  in  a  large  number  of  species  the 
mineral  matter  is  almost  entirely  absent,  and  the  skeleton 
is  almost  wholly  cartilaginous.  This  difference  in  com- 
position coincides  with  other  very  considerable  organic 
differences,  and  it  has  been  deemed  necessary  to  classify 
fishes  in  two  distinct  groups, — bony  fishes  and  cartilag- 
inous fishes.  Among  the  bony  fishes  are  the  salmon, 
the  carp,  perch,  eels,  etc.  As  examples  of  cartilaginous 
fishes  may  be  named  the  shark,  ray,  sturgeon,  and  lam- 
prey. 

The  brain,  like  that  of  batrachians,  is  formed  of 
linearly-arranged  parts.  Two  olfactory  lobes,  often 
largely  developed,  are  in  front  of  the  hemispheres,  while 
behind  them  the  optic  thalami,  followed  by  the  cerebellum, 
are  easily  seen. 

In  general  the  organs  of  sense  are  quite  well  developed. 
The  crystalline  lens  is  spherical,  the  eye  but  slightly 
convex  in  front,  and  without  eyelids. 

The  ear  comprises  only  the  internal  parts  :  in  it  there 
is  a  sac  containing  a  calcareous  stone,  often  quite  large, 
which  corresponds  to  a  calcareous  powder  found  in  the 
ears  of  mammals. 


THE  FIVE  CLASSES  OF  VERTEBRATES.       123 

The  organ  of  smell  appears  to  be  well  developed,  the 
olfactory  nerve  being  large,  and  sending  off  branches  to 
,the  nasal  sacs,  little  blind  sacs  in  the  nasal  fossae. 

The  touch  is  exercised  by  the  barbels  or  lips. 

There  appears  to  be  no  sense  of  taste. 

Eeproduction  takes  place  by  eggs.  The  fecundity  of 
the  carp,  like  that  of  many  other  fishes,  is  so  great  that 
it  has  become  proverbial.  A  female  carp  of  good  size 
contains  not  less  than  five  or  six  hundred  thousand  eggs. 
These  eggs  are  deposited  on  the  leaves  of  aqueous  plants 
in  March  or  April,  and  hatch  in  seven  or  eight  days. 
The  growth  of  the  young  is  very  rapid  ;  if  the  conditions 
are  favorable  a  young  carp  attains  in  three  years'  growth 
a  weight  of  five  or  six  pounds ;  afterwards  the  growth 
is  much  slower. 

Carp  flourish  in  ponds  as  well  as  in  rivers  whose  cur- 
rents are  slow.  They  feed  on  larvae,  worms,  grain,  aquatic 
herbs,  and  young  vegetable  sprouts ;  often,  indeed,  they 
rise  and  seize  insects  on  the  surface  of  the  water. 


CHAPTER   XII. 

• 

Review  of  the  Distinguishing  Features  of  the  Five 
Classes  of  Vertebrates. 

IN  the  preceding  chapters  we  have  taken  one  example 
from  each  of  the  five  classes  of  the  great  group  of  ver- 
tebrates. We  have  seen  the  differences  that  distinguish 
the  mammalian  dog  from  the  chicken,  and  have  studied 
the  peculiarities  in  structure  of  reptiles,  batrachians, 


124  A   COURSE   ON   ZOOLOGY. 

and  fishes.  That  which  has  been  said  of  each  type  ap- 
plies to  the  whole  class  to  which  the  type  belongs,  ex- 
cepting, of  course,  the  peculiarities  of  the  species.  We 
will  now  review  the  distinguishing  features  of  each  of 
these  classes  of  vertebrates. 

I.  All  the  mammals  are  beings  whose  organization 
presents  remarkable  analogies  with  that  of  man.  Their 
double  and  complete  circulation  starts  from  a  heart  di- 
vided into  four  compartments,  of  which  the  two  on  the 
right  are  completely  separated  from  those  on  the  left. 
The  arterial  blood  cannot,  therefore,  mix  with  the  venous 
blood  in  any  manner.  Their  respiration  is  aerial,  and  is 
effected  by  the  lungs.  They  have  a  constant  and  toler- 
ably high  temperature :  they  are  warm-blooded  animals. 
We  may  add  that  they  are  viviparous, — that  is,  the 
young  are  at  once  produced  alive, — and  that  they  nour- 
ish their  young  with  milk.  This  last  peculiarity  is  the 
cause  of  the  name  mammal,  meaning  an  animal  having 
teats.  Lastly,  their  bodies  are  usually  covered  with 
hair. 

Examples  of  mammals :  man,  monkey,  dog,  cat,  bat, 
rat,  sheep,  goat,  horse,  cattle,  seal,  whale. 

II.  Birds  have  a  complete  and  double  circulation  like 
mammals.     They  are  warm-blooded  animals.    Their  res- 
piration is  aerial  and  pulmonary,  and  they  exercise  this 
function  with  an  activity  in  perfect  proportion  to  the 
great  exercise  of  force  required  by  their  ordinary  mode 
of  locomotion.      They  are  oviparous,    their   bodies  are 
covered  with  feathers,  and   their  forelimbs  are   never 
organized  for  walking. 

Examples  of  birds :  eagle,  chicken,  parrot,  turkey, 
quail,  stork,  duck,  canary,  sparrow. 

III.  Reptiles  are  cold-blooded  animals ;  their  circula- 


THE  FIVE  CLASSES  OP  VERTEBRATES.       125 

tion  is  incomplete ;  the  two  ventricles  of  the  heart  are 
generally  in  communication  with  each  other;  the  heart 
has  then  only  three  chambers  ;  the  arterial  blood  and  the 
venous  blood  are  thus  mixed  in  the  lower  chamber,  so 
that  only  a  portion  of  the  venous  blood  goes  to  the  lungs 
for  aeration  before  passing  to  the  arteries,  and  a  portion 
of  the  arterial  blood  returns  immediately  to  the  lungs 
without  having  traversed  the  general  circulation.  Ees- 
piration  is  aerial  and  pulmonary,  but  it  is  a  function 
always  somewhat  sluggish.  Eeptiles  are  oviparous,  or 
exceptionally  ovoviviparous ;  their  bodies  are  usually 
covered  with  scales. 

Examples  of  reptiles  :  alligator,  lizard,  tortoise,  snakes. 

IV.  Batrachians  are  related  to  reptiles  by  their  gen- 
eral characters,  but  they  are  distinguished  from  these 
by  the  fact  that  during  the  early  part,  and  sometimes 
during  the  whole  course,  of  their  lives  respiration  is 
aquatic  and  is  accomplished  by  gills.  The  skin  of 
batrachians  is  naked,  having  neither  hair,  feathers,  nor 
scales. 

Examples  of  batrachians :  frog,  toad,  salamander. 

Y.  Fish,  like  reptiles  and  batrachians,  are  cold-blooded 
animals.  They  have  complete  circulation, — that  is,  there 
is  no  mixture  of  arterial  and  venous  blood ;  but  the  heart 
is  single  instead  of  double,  and  has  only  two  cavities. 
These  cavities  correspond  to  the  right  heart  of  mammals; 
they  are  traversed  only  by  the  venous  blood,  which  then 
passes  to  the  respiratory  organs.  Respiration  is  aquatic, 
and  takes  place  by  the  aid  of  gills.  Fish  reproduce  their 
kind  by  eggs  ;  several  species  are  ovoviviparous.  Their 
bodies  are  covered  with  scales. 

Examples  of  fishes :  pike,  carp,  bass,  eel,  sturgeon,  ray, 
trout,  salmon,  perch,  catfish. 

11* 


126 


A   COURSE   ON    ZOOLOGY. 


The  following  table  gives  in  resume  the  peculiarities 
of  the  five  classes  of  vertebrates :   . 


MAMMALS  .   .   . 

Respiration 

always  pul- 
monary .  . 

BIRDS  .  .  .  .   I 

'- 

( 
REPTILES  .  .    -j 

Respiration 

BATRACHIANS  , 

branchial, 

at   least  in 
early  life 

FISHES.  .  .  .   \ 

Viviparous,  suckling  the   young; 
udders ;  warm  blood ;  double  and 
complete  circulation ;  heart  with 
four  chambers;  skin  ordinarily 
covered  with  hair, 
f  Warm  blood ;  double  and  complete 
I     circulation ;     heart    with    four 

chambers;  feathers. 
fCold  blood;     circulation   double, 
but   incomplete;   heart   usually 
with  three  cavities ;  scales. 

Lungs,  in  the  adult  state;  cold 
blood;  double  but  incomplete 
circulation;  heart  with  three 
cavities ;  naked  skin. 

Permanent  gills ;  life  always 
aquatic;  cold  blood;  circulation 
single,  but  complete ;  heart  with 
two  cavities;  scales. 


CHAPTER   XIII. 
Generalities  Concerning-  the  Articulates. 

ALL  the  animals  that  we  have  so  far  studied,  however 
different  they  may  be  in  form,  structure,  and  habits,  re- 
semble one  another  in  one  point, — their  bodies  all  con- 
tain a  strong  internal  framework,  to  which  the  soft  parts 
are  attached. 

There  are  other  animals,  much  more  numerous  than 
those  in  the  division  we  have  just  studied,  in  which  the 
arrangement  of  soft  and  hard  parts  is  exactly  the  oppo- 
site of  that  in  the  vertebrates, — that  is,  the  skeleton  is 
on  the  outside,  while  the  flesh  and  muscles  are  within. 


GENERALITIES   CONCERNING   ARTICULATES.  127 

FIG.  68. 


TEGUMENTARY  SKELETON  OF  A  LOCUST,  DISARTICULATED.— C,  head ;  T.  thorax ; 
A, 'abdomen;  I,  lower  lip;  M,  mandibles;  m, jaws;  n,  antennae;  I,  pro- 
thorax  ;  PI,  first  pair  of  feet ;  II,  mesothorax ;  pn,  second  pair  of  feet ;  as, 
upper  wings ;  III,  metathorax ;  pm,  third  pair  of  feet;  ai,  lower  wings ;  1  to 
10,  joints  of  the  abdomen ;  O,  appendages. 


128  A   COURSE   ON   ZOOLOGY. 

To  this  class  belong  all  the  animals  named  by  Cuvier 
articulates  because  their  bodies  consist  of  rings  having 
articulated  ends, — that  is,  mobile  pieces  or  articles 
adapted  for  locomotion  and  for  nutrition.  According  to 
the  species  the  solid  rings  or  segments  are  furnished 
each  with  one  or  with  several  pairs  of  appendages. 

The  bodies  of  these  animals  present  three  distinct  re- 
gions, the  head,  the  thorax,  and  the  abdomen, 

The  head  is  the  front  part ;  it  is  formed  of  several 
rings,  but  these  are  so  closely  united  together  that  their 
limits  cannot  be  distinguished ;  however,  the  number  of 
appendages  indicates  the  number  of  rings  composing  the 
head.  Among  these  appendages,  some  placed  near  the 
eyes  are  called  antennae ;  others  near  the  mouth  aid  in 
the  functions  of  nutrition.  The  head  contains  the  or- 
gans of 'sense,  and  also  an  important  nerve-centre  com- 
posed of  the  cerebral  ganglions. 

The  thorax  is  composed  of  rings  that  are  sometimes 
firmly  joined  together,  sometimes  entirely  separate ;  in 
the  latter  case  they  are  usually  three  in  number.  This 
region  is  generally  quite  separate  from  the  head,  but 
sometimes  it  forms  with  the  latter  but  a  single  piece, 
which  is  then  called  cephalo-thorax. 

The  rings  that  form  the  abdomen  are  distinct  and 
vary  considerably  in  number. 

Both  the  thorax  and  the  abdomen  may  have  appen- 
dages, but  the  limbs  are  specially  related  to  the  pieces  of 
the  thorax. 

We  have  said  that  the  rings  of  the  body  and  those  of 
the  members  form  in  the  articulates  an  external  skeleton 
that  we  have  compared  to  the  internal  skeleton  of  the 
vertebrates.  It  must  not,  however,  be  supposed  that 
there  is  any  real  resemblance  between  the  two  sub- 


GENERALITIES    CONCERNING    ARTICULATES. 


129 


FIG.  69. 


stances,  which  are  essentially  dissimilar.  The  substance 
that  forms  the  skeleton  of  the  verte- 
brates is  bone,  while  that  which  makes 
up  the  skeleton  of  the  articulates  is  a 
rigid  matter  called  chitin,  that  in  most 
cases  becomes  incrusted  with  carbonate 
of  lime.  The  skeleton  of  the  vertebrates 
is  said  to  be  bony,  while  the  covering  of 
the  articulates,  and  in  general  that  of  all 
invertebrates,  is  chitinous. 

The  articulates  possess  a  distinct  diges- 
tive apparatus,  as  well  as  apparatus  of 
circulation  and  of  respiration  ;  the  latter, 
however,  are  much  simplified.  The  study 
of  the  peculiarities  of  these  apparatus 
we  will  take  up  as  we  study  the  types 
selected  for  each  of  the  classes  of  artic- 
ulates. 

In  all  articulates  the  nervous  sys- 
tem has  about  the  same  organization, 
but  this  is  so  different  from  that  with 
which  we  have  become  familiar  in  the 
vertebrates  that  it  is  entirely  character- 
istic. It  is  composed  of  a  series  of  gan- 
glionic  masses,  joined  together  in  a  long 
chain  by  nerve-filaments  or  commissures, 
The  largest  of  these  masses  are  situated 
in  the  head,  and  form  what  is  called  the 
brain  or  cephalic  ganglion,  Behind  and 
under  the  oesophagus  we  find  another 
ganglion,  called  the  suboesophageal,  joined 
to  the  cephalic  ganglion  by  two  commissures  that  circle 
around  the  oesophagus :  altogether  this  constitutes  the 
i 


IV,  nervous  system 
of  a  myriapod; 
V,  nervous  sys- 
tem of  a  caterpil- 
lar. The  subin- 
testinal  ganglia 
are  far  apart,  and 
show  distinctly 
the  chains  to 
which  they  be- 
long. 


130 


A   COURSE   ON   ZOOLOGY. 


cesophageal  ring.  Farther  back  is  the  gang-Home  chain, 
properly  speaking,  composed  of  thoracic  and  abdominal 
ganglia,  all  united  together  by  commissures.  This  whole 
chain  is,  like  the  subo3sophageal  ganglion,  placed  under 
the  intestinal  canal  so  that  the  cephalic  ganglion  alone 
is  above  the  digestive  apparatus. 

The  organs  of  sense  are  pretty  well  developed  in  the 
articulates,  and  it  is  even  possible  that  these  animals 
possess  certain  senses  different  from  ours,  and  therefore 
such  as  we  can  understand  only  very  imperfectly. 

To  review,  the  articulates  or  arthropods  are  dis- 
tinguished by  bodies  composed  of  rings  carrying  pro- 
cesses formed  of  mobile  articles,  and  by  their  ganglionic 
nervous  systems,  arranged  in  a  ventral  chain  that  is 
connected  with  a  cerebral  mass  by  an  oesophageal  ring. 

The  division  of  articulates  comprises  four  principal 
classes :  Crustaceans,  Insects,  Arachnida,  and  Myriapods, 
The  peculiarities  of  these  classes  is  as  follows : 

I.  In  Crustaceans  respiration  is  branchial  or  cutaneous. 
The  thorax  has  five  or  seven  pair  of 
limbs.  The  crayfish,  lobster,  crab, 
prawn,  and  wood-louse  are  crusta- 
ceans. 

II.  Insects  have  tracheal  respiration ; 
that  is  effected  by  means  of  tubes, 
called  tracheae  or  spiracles,  kept  open 
by  a  sort  of  coiled  spiral  thread,  and 
distributed  over  the  body  and  in  all 
the  organs.  Insects  always  have  three 
pair  of  feet,  never  more  nor  less.  Flies, 
butterflies,  moths,  and  beetles  are  in- 
sects. 
III.  In  the  Arachnida  respiration  is  sometimes  tra- 


FIG.  70. 


ENLARGED    TRACHEA 

OF  AN  INSECT. 


THE    CRAYFISH.  131 

cheal,  sometimes  pulmonary.  The  head  and  thorax,  in- 
stead of  being  separate,  as  in  the  two  preceding  groups, 
are  joined  in  a  single  piece, — the  cephalo -thorax.  All 
have  four  pair  of  limbs.  Spiders  and  scorpions  are  arach- 
nidae. 

IV.  The  Myriapods  are  distinguished  by  bodies  com- 
posed of  numerous  rings,  all  alike  after  the  head,  and 
each  carrying  one  or  two  pair  of  legs.  Consequently 
the  number  of  feet  is  quite  large  in  all  the  myriapods, 
and  they  are  commonly  called  centipedes  or  thousand- 
legs. 


CHAPTER  XIV, 
The  Crayfish. 

THE  crayfish  is  a  crustacean.  Crustaceans  owe  the 
name  to  their  hard  carapace,  stiffened  with  calcareous 
matter.  The  color  of  the  crayfish  is  variegated  blue  and 
red.  The  head  has  projecting  eyes,  said  to  be  pedicu- 
lated  or  stalked,  and  two  pair  of  antennae  of  unequal 
length.  The  mouth  is  situated  in  a  sort  of  depression, 
partly  covered  by  the  region  of  the  antenna,  and  sur- 
rounded by  six  pair  of  articulated  processes,  which  are 
only  so  many  limbs  modified  for  the  purposes  of  prehen- 
sion and  mastication  of  the  food. 

The  first  pair — one  of  which  is  at  each  side  of  the 
mouth,  and  which  are  covered  by  the  others — constitute 
the  mandibles.  The  mandibles  are  short,  thick,  and  pre- 
sent a  large  surface  and  sharp  edges  ;  they  are  specially 
adapted  for  mastication,  and  each  has  a  little  lateral 
process  called  the  maxillary  palp,  or  feeler  of  the  jaw. 


132 


A   COURSE   ON   ZOOLOGY. 


FIG.  71. 


CRAYFISH  FROM  ABOVE.— CT,  head  and  thorax ;  A,  abdomen ;  n,  internal 
antennae ;  N,  external  antennae ;  o,  eye ;  PI,  jaws  of  the  first  pair  of  walking 
feet ;  P2  to  P6,  walking  feet ;  a,  rings  of  the  abdomen ;  pq,  pieces  of  the  tail. 


THE    CRAYFISH.  133 

The  next  two  pair  are  called  the  maxillae,  although,  in 
fact,  these  members  do  not  serve  in  crushing  the  food. 
They  are  hairy  joints,  and  are  used  to  hold  the  food 
against  the  mouth  during  mastication. 

The  last  three  pair  of  peribuccal  (surrounding  the 
mouth)  limbs  are  called  the  jaw  feet ;  they  indeed  look 
like  feet,  but  they  are  kept  folded  before  the  mouth,  and 
their  use,  like  that  of  the  maxillae,  is  to  hold  the  food. 

The  thorax  of  the  crayfish  is  formed  of  segments 
which  above  are  united  in  one  large  carapace,  and  below 
carry  five  pair  of  articulated  feet,  more  or  less  lengthy 
and  hairy;  these  are  the  ambulatory  feet,  for  they  are 
used  in  walking.  Their  number,  in  the  natural  group  to 
which  belong  the  crayfish,  the  lobster,  and  the  crab,  is 
five  pair,  and  the  name  Decapods  has  been  given  to  these 
animals. 

In  the  crayfish,  the  lobster,  and  the  crab  the  first  pair 
of  ambulatory  feet  are  curiously  modified.  They  are 
terminated  by  a  sort  of  hand  formed  like  a  large  pair  of 
pincers  •  the  interior  edges  of  the  blades  of  these  strong 
pincers  are  studded  with  rounded  tubercles.  The  organ 
thus  serves  more  than  its  primary  purpose,  and  is  useful 
for  prehension.  It  is  called  the  claw. 

The  segments  of  the  abdomen  are  quite  distinct  and 
movable  one  on  the  other.  On  the  under  surface  they 
have  small  feet,  but  very  little  developed,  and  called 
false  feet,  between  which  the  female  carries  her  eggs 
after  they  have  been  laid.  The  abdomen  is  terminated 
by  a  number  of  joints  spread  out  like  a  fan,  and  forming 
the  tail. 

The  carapace  of  the  crayfish  is  hard,  but  the  animal, 
like  many  other  crustaceans,  sheds  its  coat  at  cer- 
tain seasons, — that  is,  it  abandons  its  carapace,  out  of 

12 


134 


A    COURSE   ON    ZOOLOGY. 


FIG.  72. 


CRAYFISH  SEEN  FROM  BELOW  (letters  have  the 
same  significance  as  in  the  previous  figure). 
— M,  mandibles ;  pma,  jaw  feet ;  ov,  eggs  held 
between  the  abdominal  false  feet  pa. 


which  it  comes  as 
out  of  a  case.  The 
moulting  is  accom- 
panied by  an  in- 
crease in  size.  After 
this  has  taken  place, 
the  new  shell  re- 
mains soft  for  a  cer- 
tain length  of  time ; 
then  it  also  gradu- 
ally becomes  hard, 
and  the  animal  re- 
sumes its  habitual 
life.  The  hardening 
of  the  new  shell  is 
effected  by  the  aid 
of  a  reserve  of  cal- 
careous matter  that 
the  animal  secretes 
in  its  stomach,  in  the 
form  of  white,  calca- 
reous disks,  convex 
on  one  face,  and  con- 
cave on  the  other, 
and  formerly  used  in 
medicine  under  the 
name  crab's-eyes  or 
crabstones.  When 
the  new  carapace  is 
formed,  these  con- 
cretions have  disap- 
peared, having  been 


absorbed  for  the  formation  of  the  new  shell. 


THE    CRAYFISH. 


135 


On  opening  a  cray- 
fish or  a  lobster  we 
find  that  the  interior 
of  the  head  and  of 
the  thorax  is  more 
or  less  regularly  di- 
vided into  cavities 
for  the  accommoda- 
tion of  the  muscles. 
These  divisions  are 
formed  by  internal 
processes  of  the 
shell  that  together 
form  a  sort  of  inter- 
nal skeleton.  There 
are  similar  processes 
in  the  joints  of  tl\e 
limbs,  where  they 
serve  for  the  attach- 
ment of  muscles. 

The  stomach  forms 
a  sort  of  large  pocket, 
separated  from  the 
mouth  only  by  a  very 
short  esophagus. 
This  organ  is  thus 
brought  forward  far 
into  the  head.  In 
its  posterior  half  its 
walls  are  supported 
by  a  solid  frame- 
work of  joints  that 
support  three  hard  tubercles. 


CRAYFISH  OPENED  ON  THE  BACK.  —  gn,  cere- 
bral ganglion  ;  en,  oesophageal  ganglia ;  u, 
green  gland;  E,  stomach;  mm,  muscles; 
mg,  ,stomach  teeth ;  F,  liver ;  C,  heart ;  as, 
posterior  aorta;  pb,  ab,  gills;  ao,  anterior 
aorta ;  ma,  muscles. 


These  notched  tubercles 


136  A   COURSE   ON   ZOOLOGY. 

project  into  the  stomachic  cavity,  and  a*e  so  arranged 
as  to  crush  the  food  again  just  as  it  passes  into  the  intes- 
tine which  opens  from  the  bottom  of  the  stomach. 

The  intestine  is  a  straight  tube  leading  to  the  pos- 
terior end  of  the  body. 

The  liver  is  largely  developed,  and  forms  two  masses 
of  a  yellowish  color,  divided  into  lobes  and  lobules  on 
each  side  of  the  stomach. 

The  respiratory  apparatus  consists  of  gills  or  branchiae 
that  are  located  under  the  thoracic  carapace,  which 
forms  a  sort  of  respiratory  chamber  on  each  side,  com- 
municating with  the  exterior  by  two  orifices.  One  of 
these  openings  serves  for  the  admission  of  water,  and  is 
located  on  the  outside  between  the  base  of  the  feet  and 
the  edge  of  the  shell ;  the  other  is  near  the  mouth,  and 
is  employed  for  the  exit  of  the  water.  A  plate-like  ap- 
pendage of  the  second  pair  of  jaws  moves  continually  be- 
fore this  orifice,  and  sets  up  a  current  by  which  water 
is  continually  caused  to  flow  through  the  cavities. 

FIG.  74. 


GILLS  OF  CRAYFISH  EXPOSED  (after  Huxley). 

The  heart  is  situated  just  under  the  carapace  of  the 
thorax,  and  consists  of  a  single  fleshy  pocket,  having  six 
openings,  by  which  the  oxygenated  blood  coming  from 


THE    CRAYFISH.  137 

the  gills  may  penetrate  into  its  cavity.  This  heart  is 
contained  in  a  sort  of  sac  or  sinus  that  receives  directly 
the  blood  coming  from  the  gills.  The  heart  then  forces 
the  blood  it  contains  into  the  arterial  vessels.  These 
are  an  anterior  aorta,  for  the  head,  eyes,  and  other 
processes,  and  a  posterior  aorta,  which  soon  divides  into 
a  dorsal  branch  and  the  ventral  branch,  and  these  pene- 
trate into  the  interior  of  the  organs,  and  reach  the  lower 
surface  of  the  body,  where  they  distribute  the  blood  in 
front,  behind,  to  the  feet,  and  the  neighboring  organs. 
There  are  no  veins  ;  after  circulating  in  the  arteries,  the 
blood  penetrates  into  interorganic  spaces,  sorts  of  com- 
municating chambers,  situated  between  the  organs  and 
the  muscles,  and  thus  returns  to  the  gills. 

The  blood  of  the  crayfish  is  colorless  or  somewhat 
bluish.  The  nervous  system  is  ganglionic,  consisting,  as 
we  have  seen  in  the  chapter  on  generalities,  of  a  cerebral 
ganglion,  joined  by  an  cesophageal  chain  with  a  double 
chain  of  ganglia,  extending  from  one  end  of  the  body  to 
the  other. 

The  organs  of  sense  cannot  be  well  understood,  ex- 
cepting the  eyes,  which  are  two  in  number  and  stalked. 

The  sense  of  touch  is  exercised  by  the  antennae,  and 
perhaps  also  by  the  palps  that  form  part  of  certain  buc- 
cal  processes. 

Crayfish  live  in  fresh  water,  preferring  rocky  and 
shallow  streams.  They  hide  under  stones  and  in  holes, 
which  they  leave  rarely  except  when  in  search  of  their 
food,  consisting  of  mollusks,  fish,  worms,  shreds  of  rotten 
flesh,  etc.  They  are  very  voracious,  and  gorge  themselves 
with  all  animal  matters  coming  within  their  reach. 

Crayfish  lay  eggs  which  remain  attached  in  clusters 
to  their  abdominal  false  feet.  These  eggs  are  developed 

12* 


138  A    COURSE   ON    ZOOLOGY. 

without  undergoing  metamorphosis,  which  is  not  the  case 
with  all  crustaceans.  The  spring  or  rock  lobster,  for 
example,  passes  through  metamorphoses.  Before  ar- 
riving at  adult  size,  the  crayfish,  crab,  and  lobster  moult 
a  number  of  times, — at  least  thirty.  During  all  this 
time  the  animal  does  not  change  in  form ;  it  simply 
grows  larger.  While  without  a  hard  shell  the  creature 
is  perfectly  helpless,  and  lies  hidden  in  some  crevice. 


CHAPTER   XV. 
The   Beetle. 

As  a  representative  of  the  great  division  of  insects,  we 
select  one  that  is  known  throughout  the  whole  world, 
and  which  is  far  too  abundant  in  many  agricultural  coun- 
tries. It  is  the  cockchafer ;  but  almost  any  beetle  would 
answer  as  well. 

When  we  examine  a  beetle  we  at  once  notice  that  the 
animal  as  a  whole  is  made  up  of  three  distinct  parts, — 
head,  thorax,  and  abdomen.  Each  of  these  parts  is  en- 
closed in  an  envelope,  consisting  of  hard,  horny  sub- 
stance that  forms  the  external  skeleton ;  under  this 
envelope  are  attached  the  muscles,  and  within  it  are  sus- 
tained and  protected  the  soft  parts.  It  is  composed  of  a 
series  of  strong  rings,  joined  together  edge  to  edge  by 
the  intervention  of  a  more  flexible  membrane  that  allows 
a  certain  amount  of  motion.  The  arrangement  of  these 
rings  is  easily  seen  on  the  abdomen  of  the  beetle;  in 
other  parts,  as  the  head  and  thorax,  it  is  less  marked. 
It  may,  however,  be  noticed,  and  the  same  applies  to  all 


THE    BEETLE.  139 

insects  without  exception,  that  the  thorax  is  composed 
of  three  segments, — an  anterior,  called  the  prothorax,  a 
middle  one,  the  mesothorax,  and  a  posterior,  the  meta- 
thorax.  To  each  of  these  is  attached  a  pair  of  legs. 

The  head  of  insects  is  provided  with  special  organs, 
called  antennae ;  they  are  a  sort  of  horns  of  very  varia- 
ble form,  and  composed  of  rings  articulated  end  to  end. 
The  antennae  are  gifted  with  great  mobility,  and  most 
probably  serve  to  enable  the  creature  to  recognize  by 
touch  the  nature  of  surrounding  objects.  In  the  beetle 
these  organs  are  terminated  by  a  series  of  superposed 
plates  which  unfold  like  the  leaves  of  a  fan. 

Beside  the  antennae  and  near  the  mouth  are  the  eyes, 
which  have  a  structure  altogether  peculiar.  They  have 
no  eyelids,  and  their  surface,  which  is  very  prominent 
and  bulging,  presents  the  appearance  of  a  hemisphere 
cut  in  facettes.  On  examination  with  a  microscope,  or 
even  with  a  simple  magnifying  glass,  it  is  found  that 
each  facette  corresponds  to  a  distinct  eye,  and  that  the 
entire  eye  is  in  reality  composed  of  a  large  number 
of  little  eyes  placed  very  close  together :  sometimes 
there  are  several  thousand  facettes.  Independent  of 
these  multiple  eyes,  several  species  have  two  or  three 
other  eyes,  which  are  simple,  and  arranged  in  the  form 
of  a  triangle  in  the  forehead.  These  simple  eyes  are 
called  ocellae,  to  distinguish  them  from  the  compound 
eyes,  composed  of  facettes,  which  are  the  only  ones  pos- 
sessed by  the  beetle. 

Underneath  the  head  is  the  buccal  orifice.  As  in  the 
crustaceans,  this  orifice  is  surrounded  by  modified  limbs 
that  are  used  in  mastication  by  insects  that,  like  the 
beetle,  masticate  their  food. 

We  distinguish  a  pair  of  mandibles,  hard,  horny,  curved, 


140 


A  COURSE  ON  ZOOLOGY. 


and  sharp,  capable  of  tearing  and  crushing;  then  a  pair 
of  jaws  formed  by  hairy  joints.  Each  jaw  has  a  palp 
composed  of  three  joints,  and  called  the  maxillary  palp. 
'These  two  pair  of  processes  are  covered  above  by  a 
plate  that  prolongs  the  head  in  front,  and  is  known  as 
the  labrum.  Underneath  the  labrum,  and  consequently 
below  the  processes  just  described,  is  another  plate  called 
the  lower  lip,  or  labium,  which  carries  a  pair  of  palps 
known  as  the  labial  palps. 

FIG.  75. 


HEAD  OF  MAY-BUG  (the  middle  figure  is  the  whole  head  seen  from  below, 
while  around  it  are  the  separate  pieces  making  up  the  mouth).— L,  la- 
brum; M,  mandibles;  m,  jaw,  with  the  maxillary  palp  m' ;  I,  lower  lip, 
with  the  labial  palp  I'. 

This  organization  of  the  mouth  is  found  with  very 
slight  differences  in  all  masticating  insects  ;  in  others, 


THE   BEETLE. 


141 


the  joints  are  modified  to  form  a  proboscis,  either  long 
and  coiled  in  a  spiral,  as  in  the  butterfly,  or  short  and 
straight,  as  in  the  fly. 

We  have  said  that  the  thorax  carries  the  legs.  The 
beetle  has  six.  The  existence  of  these  three  pair  of  legs 
is  a  general  and 
distinguishing  fea- 
ture of  the  order 
of  insects.  Each 
leg  is  composed  of 
several  joints  ar- 
ticulated together, 
which  are  named, 
starting  from  the 
end  next  the  body, 
the  thigh,  the  leg, 
and  the  tarsus, 
which  terminates 
in  hooks,  claws, 
or  other  processes, 
according  to  the 
habits  of  the  par- 
ticular '  SDecies  DISARTICULATED  BEETLE.— A,  the  head ;  F,  the 

abdomen ;  between  A  and  F,  the  three  rings  of 

Each  of  these  the  thorax ;  a,  maxillary  palps ;  6,  labial  palps ; 
joints  is  a  SOrt  Of  c-  mandibles;  d,  antennae;  B,  prothorax,  with 

first  pair  of  legs ;  C,  wing-covers  or  elytra ;  D, 

horny  tube,  m  the  functional  wings;  H  and  I,  two  posterior  pair 
interior  of  which  of  legs;  E,  coxa  of  leg,  with  projecting  trochan- 

ter ;  e,  femur;  /,  tibia  ;  g,  tarsal  joints. 
are  arranged   the 

motor  muscles.  The  legs  of  the  beetle  end  in  sharp 
hooks ;  besides,  they  are  furnished  with  piercing-points 
or  spines,  and  this  explains  why  it  is  difficult  to  remove 
a  beetle  from  leaves  or  stuff  to  which  it  is  clinging.  The 
formation  of  the  feet  enables  the  insect  to  maintain  itself 


142  A   COURSE   ON   ZOOLOGY. 

firmly  on  leaves  and  branches  from  which  it  would  Other- 
wise be  shaken  by  the  lightest  breeze. 

To  the  thorax  are  likewise  attached  the  organs  by 
whose  aid  the  beetle  transports  itself  through  the  air. 
Some  insects,  much  fewer  than  the  others,  have  no  wings; 
some,  such  as  the  house-fly,  have  two ;  others,  such  as 
the  bee,  the  dragon-fly,  and  the  beetle,  have  four.  But 
while  the  four  wings  of  the  dragon-fly  are  flexible,  thin, 
and  transparent  like  gauze,  in  the  beetle  two  are  hard 
and  horny,  and  serve  only  in  fact  as  covers  for  the  other 
two.  The  latter  are  very  delicate,  very  fragile,  and  much 
larger,  and  during  repose  they  are  folded  up  and  pro- 
tected beneath  their  covers.  The  hard  wings  are  called 
elytra,  sheaths,  or  wing-cases. 

The  membranous  wings  are  attached  to  the  meso- 
thorax,  and  the  elytra  are  fixed  to  the  metathorax.  The 
prothorax  is  designated  more  particularly  as  the  corselet, 
and  carries  only  the  first  pair  of  legs  and  the  dorsal  ap- 
pendages. This  segment  is  very  largely  developed  in  its 
dorsal  part,  and  forms  the  greater  part  of  the  thorax ;  the 
remainder  is  concealed  by  the  wings. 

Insects  differ  from  animals  having  an  interior  skeleton 
not  only  by  the  inverse  arrangement  of  their  hard  and  soft 
parts :  the  whole  organization  presents  profound  modi- 
fications which  we  must  study. 

The  digestive  apparatus  includes  an  oesophagus,  then 
an  enlargement  or  gizzard,  followed  by  a  stomach 
studded  with  pepsin  glands.  Then  comes  the  intestine, 
more  or  less  lengthy  and  coiled.  There  is  no  liver; 
three  pair  of  coiled  tubes  open  into  the  intestine  at  its 
junction  with  the  stomach,  and  appear  to  fill  at  the  same 
time  the  functions  of  liver  and  of  urinary  apparatus. 
They  are  called  Malpighian  tubes. 


THE    BEETLE. 


143 


The  functions  of 
circulation  and  of 
respiration  are  ac- 
complished in  in- 
sects in  the  most 
simple  manner.  Ex- 
cepting a  movement 
that  is  visible  in  a 
vessel  located  in  the 
region  of  the  back, 
called  the  dorsal  ves- 
sel, there  is,  so  to  say, 
no  circulation ;  the 
blood  penetrates  into 
the  organs  .as  water 
soaks  into  a  sponge, 
and  appears  to  be 
stagnant  in  the  la- 
cunae of  the  tissues. 
Nevertheless,  this 
blood,  like  that  of 
man  and  other  higher 
animals,  must  be 
aerated  by  contact 

DIGESTIVE  APPARATUS  OF  THE 
MAY-BUG.— a,  antennae;  p, 
maxillary  palps ;  te,  cesoph- 
agus  and  craw ;  e,  stomach  ; 
t,  intestine ;  r,  rectum ;  mt 
Malpighian  tubes.  One  of 
these  tubes  is  in  its  natu- 
ral position,  close  to  the 
digestive  apparatus;  the 
other  has  been  removed  to 
show  its  structure. 


FIG.  77. 


144  A   COURSE   ON   ZOOLOGY. 

with  the  atmosphere ;  now,  as  the  blood  does  not  circu- 
late, as  insects  have  no  lungs  nor  gills  to  bring* the  vital 
fluid  in  contact  with  the  air,  this  contact  must  take 
place  throughout  the  whole  body  of  the  creature  wher- 
ever the  blood  may  be,  and  this  is  what  actually  occurs. 
The  segments  that  compose  the  external  envelope  are 
pierced  laterally  with  small  holes  called  stigmata,  and 
these  open  into  little  tubes  called  tracheae,  which  dis- 
tribute the  air  throughout  the  interior  of  the  organism 

FIG.  78. 


CIRCULATION  OP  AN  INSECT.— a,  c,  c,  dorsal  vessel.    The  arrows  indicate  the 
direction  of  the  blood. 

by  dividing  up  into  small  branches  of  exceeding  fine- 
ness that  penetrate  into  all  the  organs.  The  walls  of 
the  trachesB  are  supported  by  a  coiled  fibre,  and  so  are 
always  kept  open  for  the  free  circulation  of  air. 

The  nervous  system  is  ganglionic,  and  nothing  need 
be  said  concerning  it  more  than  has  been  given  in  Chap- 
ter XIII. 

To  conclude  this  brief  description  of  insect  organiza- 
tion, we  must  consider  one  fact  that  we  have  noticed  as 
an  exception  in  the  division  of  vertebrates,  and  which  ac- 
quires a  remarkable  generality  in  the  articulates.  This 
is  metamorphosis. 

Insects  lay  eggs,  usually  in  large  numbers,  and  these 


THE    BEETLE. 


145 


FIG.  79. 


the  female,  guided  by  wonderful  instinct,  deposits  in 
places  best  adapted  for  their  hatching.  After  a  certain 
time  there  bursts  from  each  egg  a  soft  creature,  whose 
form  is  ordinarily  that  of  a  worm.  This  creature  is  never 
winged,  often  has  no  feet,  and  is  very  different  from  the 
insect  that  gave  it  birth.  It  is  called  a  larva.  It  eats, 
grows,  and  regularly  accomplishes  all  the  acts  of  its  life, 
but  in  a  manner  often  strangely  different  from  that  ob- 
served later,  when  the  same  insect  has  arrived  at  com- 
plete maturity.  Thus,  the  May-bug,  which  lives  in  the 
air,  on  trees  and  plants,  and  which  eats  leaves,  has  for  its 
larva  a  white  maggot  that  lives  deep  in  the  ground  and 
feeds  on  roots. 

At  the  end  of  a  second  interval  of  time,  varying  ac- 
cording to  the  species,  the  larva,  after  having  several 
times  changed  its 
skin,  ceases  to 
feed,  and  becomes 
motionless ;  its 
form  becomes 
obliterated,  and 
the  worm  be- 
comes a  nymph  or 
chrysalis.  While 
in  this  condition 
it  begins  to  show 
the  various  parts 
that  character 
ize  the  individual 
when  fully  devel- 
oped. 

At  last,  at  the  end  of  the  third  lapse  of  time,  the 
perfect  insect  appears,  and  does  not  long  delay  in  pro- 
a        k  13 


COCKCHAFER  (Melolontha  vulgaris).—a,  full-grown 
larva ;  b,  pupa ;  c,  perfect  insect. 


146  A   COURSE    ON   ZOOLOGY. 

* 

ducing  eggs  which  undergo  the  same  series  of  metamor- 
phoses. 

The  fecundity  of  insects  is  enormous  ;  fortunately,  the 
female  of  the  ordinary  beetle  lays  only  thirty  or  forty 
eggs,  which  she  deposits  in  a  hole  made  by  herself  in  the 
ground,  and  which  she  covers  with  earth.  From  these 
eggs  come  the  larvae,  which  become  perfect  insects  only 
after  three  or  four  years,  and  which  during  this  time 
make  great  ravages  on  ihe  roots  and  subterranean  parts 
of  vegetables.  In  winter  the  larvae  bury  themselves 
deep  in  the  ground,  and  pass  the  cold  season  in  a  sort 
of  lethargic  sleep.  In  the  spring  they  come  up  towards 
the  surface,  and  if  their  moment  of  metamorphosis  is 
come,  they  appear  as  beetles  in  early  summer. 

During  the  heat  of  day  the  perfect  beetles  hide  un- 
der leaves,  on  which  they  feed,  cutting  out  as  they  eat 
curious  and  capricious  figures  ;  in  the  evening  they  begin 
to  move  about  with  a  noisy,  ill-directed  flight.  In  some 
years  certain  varieties  of  beetles  appear  in  enormous 
numbers,  and  devastate  the  fields  of  the  farmers,  leaving 
them  absolutely  bare  of  verdure. 


CHAPTER   XVI. 
The  Spider. 

THE  spider  belongs  to  the  class  Arachnida,  which,  like 
insects  and  crustaceans,  forms  part  of  the  division  Ar- 
ticulates. 

The  body  of  the  spider  is  composed  of  but  two  parts, 
the  head  and  thorax  together  forming  but  a  single  joint, 
called  the  cephalo-thorax.  This  joint  carries  on  its  dorsal 


THE    SPIDER. 


147 


surface  a  number  of  simple  eyes,  variously  arranged, 
according  to  the  species,  but  always  embracing  a  very 
large  field  of  vision.  Underneath  the  cephalo-thorax  are 
inserted  eight  legs,  terminated  by  notched  hooks ;  this 
number  of  feet  is  constant  in  the  spiders,  and  distin- 
guishes the  latter  from  insects,  all  of  which  have  six. 

The  abdomen  is  attached  to  the  anterior  portion  of 
the  body  by  a  very  thin  stalk ;  it  is 
soft  and  round.  Behind  it  is  furnished 
with  the  spinning  glands,  which  form 
rounded  eminences  ;  these  are  four  or 
six  in  number,  and  are  pierced  with  a 
large  number  of  minute  holes  open- 
ing, into  internal  canals  filled  with  a 
gummy  matter  analogous  to  silk. 
This  matter  produces  threads  of  ex- 
ceeding fineness,  for  more  than  a 
thousand  would  be  required  to  make 
the  thickness  of  a  human  hair.  As 
these  threads  leave  the  spinning 
glands  the  spider,  by  the  aid  of  its  feet, 
notched  like  combs,  unites  them  in  a 
single  filament,  which  it  draws  out  SPIDER  WITH  THE  LEGS 
from  the  point  at  which  it  has  first  ™T  OFF-  The  fi*ure 

shows  the  union  of 

attached  one  end  by  pressure  of  the      the  head  and  thorax 

abdomen.      With    these  threads   the 

spider  weaves  its  web,  or  stretches  a 

bridge  from  one  place  to  another,  or 

descends  to  the  ground,  as  it  desires. 

And  with  the  same  substance  it  lines 

its  hiding-place,  or  makes  the  silky 

sac  in  which  it  deposits  its  eggs.     The  long  white  fibres 

sometimes    seen  floating   in    the   air,   and   often   called 


in  one  piece,  forming 
the  cephalo-thorax. 
—  c,  chelycera;  pm, 
jaws ;  pi  to  p4,  the  four 
pair  of  feet;  r,  res- 
piratory sacs;  s,  stig- 
mata ;  a,  anus ;  /, 
spinners. 


148 


A    COURSE    ON    ZOOLOGY. 


gossamer  threads,  are  only  the  debris  of  innumerable 
webs  woven  during  the  summer  by  spiders,  with  which 

the  country  places  are  filled. 
pIG>  si.  The  webs  are  broken  up  by 

FIG.  82. 


MUCH-ENLARGED  SPIDER'S  FOOT,  show- 
ing the  toothed  claws,  gg. 


EXTREMITY  OF  A  SPIDER'S  ABDOMEN, 
enlarged  to  show  the  spinning  ap- 
paratus, //. 


the  winds  and  scattered  broadcast,  and  often  in  their 
folds  carry  off  the  creature  that  has  woven  them. 

All  spiders  are  spinners,  but  all  do  not  weave  webs. 
Some  of  them  simply  line  their  homes  with  a  sort  of 
wadding,  and,  hidden  in  the  hole  of  a  wall,  or  behind  a 
clump  of  earth,  remain  in  ambush,  motionless  and  pa- 
tient, waiting  until  some  prey  comes  within  their  reach ; 
they  then  like  a  flash  spring  out  with  the  impetuosity 
and  the  ferocity  of  a  tiger,  and  use  their  web  to  tie  up 
and  paralyze  their  victim. 

Those  that  construct  webs  do  not  all  work  in  the  same 
manner.  Some  weave  a  sort  of  circular  net- work,  of  which 
certain  lines  form  rays  from  the  centre  to  the  circumfer- 
ence, while  other  finer  ones  hold  them  together ;  these 
are  closer  and  closer  towards  the  centre.  Others  select 
the  angle  of  a  wall,  in  which  they  arrange  a  horizontal, 
triangular  web,  closely  woven  together;  they  then  live 
in  a  cylindrical  canal  placed  at  one  of  the  angles,  and 


THE    SPIDER.  149 

throw  out  isolated  threads,  connecting  their  lair  with 
the  edges  of  the  trap  ;  in  this  case,  as  soon  as  an  unfor- 
tunate fly  touches  the  web  the  scarcely-perceptible  shock 
is  communicated  by  the  conducting  threads  to  the  spider, 
who  rushes  out  and  strangles  his  prey  by  enveloping  it 
with  new  threads,  at  the  same  time  paralyzing  it  by 
the  thrust  of  a  poisonous  dart  with  which  the  end  of 
his  jaw  is  armed.  Then  he  fixes  himself  on  his  immobile 
victim,  sucking  the  juices  and  humors,  and  abandoning 
the  cadaver  only  when  it  is  reduced  to  a  dry  and  empty 
shell. 

Spiders  eat  their  kind :  two  of  these  creatures  put 
together  begin  a  mortal  combat,  and  the  vanquished  is 
eaten  by  the  victor.  This  natural  ferocity  has  been  the 
cause  of  the  failure  of  all  efforts  to  raise  colonies  of 
spiders,  efforts  undertaken  with  the  object  of  utilizing 
their  silky  secretion,  which  is  analogous  to  that  of  the 
silk-worm. 

The  buccal  apparatus  of  the  spider  is  very  powerful ; 

FIG.  83. 


m 

CEPHALOTHORAX  OF  SPIDER,  FROM  THE  SIDE.— c,  claws;  pm,  jaws;  pi,  p2,  the 
first  two  feet ;  g,  hooks. 

it  consists  of  a  pair  of  mandibles  or  forceps  having 
two  joints.  The  upper  one  is  a  sharp  hook,  very  hard, 
and  having  near  its  point  a  hole  for  the  projection  of  a 

13* 


150 


A    COURSE    ON    ZOOLOGY. 


poisonous  liquid  secreted  by  a  gland  situated  at  the  base 
of  the  organ.  A  pair  of  jaw-feet  with  six  joints  com- 
pletes the  buccal  apparatus. 

The  digestive  apparatus  consists  of  a  narrow,  cylin- 
drical oesophagus,  opening  into  a  large  pocket,  which 
empties   into   a   second    stomach 
that  is  followed  by  the  intestine. 

Respiration  is  effected  by  means 
of  tracheae,  some  of  which  are  so 
enlarged  as  to  form  a  kind  of 
lungs,  and  hence  the  respiration 
of  spiders  is  sometimes  called 
pneumotrachean,  to  distinguish 
them  from  other  arachnida  whose 
respiration  is  purely  trachean, 
like  that  of  insects. 

The  circulation,  as  in  insects,  is 
accomplished  by  means  of  a  dorsal 
vessel  that  supplies  the  arteries, 
the  venous  blood  circulating  in 
interorganic  lacuna}. 

The  nervous  system  of  the 
arachnida  consists  of  two  gan- 
glionic  masses,  a  cephalic  ganglion, 
situated  above  the  oesophagus,  and 
a  thoracic  ganglion,  placed  below 
it.  The  latter  represents  the 

thoracic  and  abdominal  ganglia  joined  in  one,  and  sends 
nerves  to  the  legs  and  to  the  abdomen.  This  coalescence 
of  ganglia  occurs  in  some  crustaceans  and  also  in  some 
insects ;  it  is  not  characteristic  of  spiders. 

Spiders  reproduce  their  species  by  means  of  eggs,  from 
which  the  young  creatures  are  hatched  directly  without 


DIGESTIVE  APPARATUS  OF 
SPIDER. — ce,  oesophagus ;  a, 
stomach ;  b,  ramifications 
of  the  stomach  ;  d,  intes- 
tines ;  e,  glandular  tubes ; 
/,  rectum ;  c,  urinary  ca- 
nals. 


THE    SPIDER.  151 

metamorphosis.  The  eggs  are  deposited  in  a  delicate 
soft  sac  spun  by  the  female  spider,  and  remain  en- 
closed in  this  until  the  hatching.  Spiders  that  spin 
webs  fasten  this  sac  to  their  dwellings,  while  migra- 
tory spiders  attach  it  to  their  abdomens  and  carry  it 
around  with  them.  The  hatching  occurs  in  about  a  fort- 
night, and  the  mother  provides  for  her  young  until  they 
are  able  to  take  care  of  themselves ;  then  she  abandons 
them.  When  once  the  family  bonds  are  broken,  broth- 
ers and  sisters  have  no  mercy  one  for  the  other,  nor 
would  they  receive  any  from  the  mother  who  has  reared 
them. 

The  species  of  spiders  are  very  numerous,  and  the 
bites  of  very  few  of  them  produce  any  alarming  symp- 
toms. Among  those  whose  bites  appear  dangerous  most 
prominent  is  the  tarantula  of  the  West  Indies,  whose 
poison  generally  produces  grave  symptoms.  The  bite 
of  other  spiders  may  occasion  some  swelling  of  the  part 
bitten,  but  usually  there  is  no 
general  intoxication.  The  domes-  FIG.  85. 

tic  spiders  that  make  their  homes 
in  our  dwellings  usually  select  a 
corner  between  the  ceiling  and 
the  walls ;  they  prefer  stables,  the 
only  places  in  which  they  ap- 
pear to  render  service  to  men  COMMON  SPIDER. 
by  diminishing  the  number  of 

insects  that  annoy  cattle ;  the  spiders  that  infest  cellars 
are  like  the  preceding.  Then  we  have  the  field-spiders 
that  weave  their  nets  in  meadows  and  live  in  silk-lined 
holes ;  those  that  make  between  two  branches  of  a  tree 
or  bush  vertical  webs  in  very  regular,  circular,  or  po- 
lygonal forms,  and  live  in  the  centre ;  lastly,  the  wolf- 


152  A    COURSE    ON    ZOOLOGY. 

like  spiders  that  hold  themselves  in  ambush,  jumping 
out  on  their  prey  as  it  passes,  or  even  chasing  it  in  its 
flight. 

Two  species — the  trap-door  spider  and  the  water-spider 
— are  particularly  curious  in  their  habits,  exercising  great 
ingenuity  in  the  construction  of  their  homes.  The  trap- 
door spider  is  found  in  Africa,  Italy,  and  the  south  of 
France  ;  its  form  is  much  like  that  of  the  common  spider. 
It  digs  in  a  dry  and  sloping  soil  a  cylindrical  hole  from 
four  to  twelve  inches  deep,  which  it  lines  with  a  soft 
coating  of  silk,  and  makes  the  entrance  as  round  as  if  it 
were  traced  with  a  compass.  It  then  makes  a  thin  but 
strong  and  regular  cover  of  clay,  which  it  fixes  to  one  edge 
of  its  hole  by  means  of  an  elastic  hinge  which  allows  the 
door  to  be  raised  but  at  once  closes  it  again.  The  out- 
side of  the  door  is  rough  and  irregular,  and  cannot  be 
distinguished  from  the  surrounding  earth ;  the  inside  is 
smooth,  excepting  a  few  small  notches  on  the  edge  oppo- 
site the  hinge.  If  we  try  to  lift  the  door  of  a  hole  con- 
taining a  trap-door  spider,  we  feel  a  strong  resistance, 
sometimes  so  great  as  to  make  the  raising  of  the  door  a 
matter  of  considerable  difficulty.  After  having  gently 
opened  the  door  we  see  that  the  little  creature  has  put 
the  hooks  of  two  of  his  legs  in  the  small  notches  we 
have  mentioned,  and  with  the  other  feet  is  clinging  to 
the  walls  of  his  tube,  and  that  it  is  he  who  has  been 
holding  shut  the  door. 

The  water-spider,  although  it  can  live  under  water, 
possesses,  like  all  other  arachnida,  aerial  respiration, 
and  it  procures  its  supply  of  air  in  an  interesting  man- 
ner. Coming  to  the  surface  of  the  water  it  puts  out  its 
abdomen,  which  is  covered  with  a  sticky,  greasy  matter, 
then,  suddenly  plunging  in,  it  carries  down  a  bubble  of 


THE    SPIDER. 


153 


air  that  it  disengages  under  the  leaf  of  some  aquatic 
plant,  and  weaves  around  the  bubble  a  tissue  that  keeps 
it  from  moving  away  ;  the  spider 
then  goes  up  and  gets  another  FIG.  86. 

bubble  in  the  same  manner, 
brings  it  down,  and  adds  it  to  the 
first.  By  repeating  these  oper- 
ations enough  air  is  collected  to 
last  some  time,  and  the  little 
creature  now  encloses  the  whole 
in  a  closely-woven  net,  and 
weaves  for  itself  a  chamber  as 
large  as  a  walnut,  having  an 
opening  below  for  ingress  and 
egress.  The  water-spider  is  car- 
nivorous, like  all  other  spiders, 
and  feeds  indifferently  on  ter- 
restrial and  aquatic  insects ; 
when  it  has  seized  a  prey,  the 
latter  is  attached  to  a  thread 
and  dragged  into  the  den  for 
consumption  at  leisure.  The 
water-spider  is  found  in  most  calm  and  stagnant  waters. 
The  largest  of  the  arachnida  is  the  marine  species, 
called  the  king-crab ;  it  is  common  on  our  Atlantic  coasts. 


UNDER  SURFACE  OF  A   KING- 
CRAB  (Limulus  polyphemus). 


154 


A    COURSE    ON    ZOOLOGY. 


FIG.  87. 


CHAPTER  XVII. 

Worms — Parasites — General    Character   of    Anar- 
thropoda. 

UNDER  the  name  worms  or  annelides  are  designated 
creatures  of  a  class  that  resembles  the  articulates,  be- 
cause the  bodies  of  its  members  are  composed  of  rings 
joined  end  to  end  and  movable  one  on  the  other;  but 
the  anarthropoda  differ  from  the  articulates  in  that  they 

never  have  limbs  composed 
of  articulated  joints.  Many 
of  them  have  no  limbs 
whatever,  and  when  such 
appendages  are  present, 
they  are  reduced  to  simple 
rounded  prominences  car- 
rying stiff  hairs,  called 
cirri. 

The  order  of  anarthro- 
poda includes  two  impor- 
tant classes,  the  worms  and 
the  parasites  or  entozoa. 

WORMS. 

Most   species  of  worms 
have  red  blood ;  their  res- 
SERPULA    CONTORTUPLICATA     (with     piration  is  either  branchial 

expanded  gills)  on  the  back  of  an  mi     . 

oyster-sheii.  or  cutaneous.     Their  appa- 

ratus of  locomotion  consists 

sometimes  of  cirri  variously  grouped  on  fleshy  tubercles, 
sometimes  of  short  ventral  hairs,  sometimes  of  suckers. 


WORMS. 


155 


Those  worms  furnished  with  hair  form  the  order  seti- 
gera  or  chetopoda,  while  the  others  are  called  asetigerous 
or  apoda. 

Among  the  setigerous  worms  are  some  that  live  in 
tubes  that  they  construct ;  they  are  the  tubicolae  ;  others, 
that  have  no  regular  holes,  are  called  wandering 
worms. 

The    tubicolate   annelidans  inhabit  the  strong  tubes 
that  are  often  found  covering  rocks,  stones,  and  other 
submarine  masses;  among  them  the.  most  common  is 
the  serpula  ;   their  tubes  are  found  in  great 
numbers  on  the  shells  of  scallops,  and  if  one  of  FIG.  88. 
these  shells,  freshly  taken  from  the  sea,  be  im- 
mersed in  salt  water,  the  creatures  come  out  of 
their  tubes  and  spread  out  their  gills  like  fan- 
shaped  crests,  red  or  blue  in  color,  and  having 
branches  of  exceeding  delicacy. 

The  lobworm,  which  is  a  type  of  the  wander- 
ing species,  lives  in  the  sand  of  rivers,  and  is 
used  as  bait  in  fishing. 

Earthworms  are  the  only  annelides  that  are 
not  aquatic.  They  live  in  moist  soils,  feeding  on 
animal  and  vegetable  debris;  they  sometimes 
appear  to  render  important  service  to  agricul- 
ture by  breaking  up  and  rendering  porous  soils 
that  are  too  compact  because  of  a  large  pro- 
portion of  clay.  Earthworms  have  no  gills, 
and  respire  through  their  skin  ;  they  are  thus 
distinguished  from  the  lobworms  and  tubico- 
lidse,  both  of  which  have  gills.  They  have  very 
short  hairs  on  the  ventral  surface,  but  they 
use  these  hairs  in  locomotion,  arid  must  therefore  be 
classed  as  setigera. 


LOBWORM 
(Areni- 
col.  pisca- 
torum). 


156 


A    COURSE    ON    ZOOLOGY. 


The  leech,  on  the  contrary,  has  neither  bristles  nor 
hairs,  but  at  each  end  of  its  body  is  a  sucker,  by  which 
locomotion  is  accomplished.  The  mouth  is  situated  at 
the  bottom  of  the  anterior  sucker;  it  has  three  little 
triangular  jaws,  each  armed  with  two  rows  of  sharp 
teeth,  that  can  cut  through  the  human  skin  and  that 
of  other  animals,  leaving  a  Y-shaped  incision.  There 
are  several  species  of  leeches ;  all  are  carnivorous,  and 
several  are  used  in  medicine,  the  most  valuable  being 
known  as  the  medicinal  leech.  To  supply  the  demand 
for  leeches,  these  annelides  are  now  bred  in  large  numbers 
in  artificial  ponds,  where  they  can  find  conditions  favor- 
able to  their  multiplication. 

FIG.  89. 


THE  MEDICINAL  LEECH  (Hirudo  medicinalis). 

The  manner  of  nutrition  of  the  leech  requires  in  the 
structure  of  its  digestive  apparatus  profound  modifica- 
tions of  the  similar  organs  that  we  have  thus  far  exam- 
ined. The  simple  tube  that  exists  in  nearly  all  worms 
is  replaced  by  a  series  of  eleven  pockets  or  chambers, 
spread  out  on  the  sides  and  communicating  successively 


WORMS. 


157 


FIG.  90. 


with  one  another;  the  intestine  terminates  on  the  back 
at  the  base  of  the  posterior  sucker;  in  these  chambers 
the  creature  stores  the  blood  which  it  takes  in  at  its 
anterior  sucker.  Like  all  worms,  the  leech  is  made  up 
of  rings,  of  which  it  has  ninety-five.  Powerful  muscles 
are  attached  to  the  skin,  and  enable  it  to  contract  with 
great  force.  It  then  takes  the  form  of  an  olive,  while 
when  the  muscles  are  relaxed  it  stretches  out  like  a  long 
ribbon. 

As  in  all  worms,  the  nervous  system  consists  of  a  gan- 
glionic  chain  united  by  an 
oesophageal  band  with  a 
bilobar  anterior  ganglion. 
The  eyes  are  ten  in  number, 
being  ocular  points  situated 
on  the  upper  lip. 

Certain  creatures  that 
were  long  considered  to  be 
infusoria  are  properly  con- 
sidered among  the  worms : 
they  are  the  rotatoria. 
These  are  microscopic  crea- 
tures, furnished  in  front 
with  two  or  more  ciliary 
lobes.  Cilia  are  a  sort  of 
very  fine  hairs  animated 
with  a  continual  motion, 
which,  however,  can  be  ar- 
rested at  the  will  of  the  ani- 
mal ;  the  movements  of  the 
cilia  are  called  vibratile  movements.  These  creatures 
can  support  a  state  of  great  desiccation  and  also,  after 
drying,  a  tolerably  high  temperature,  and  yet,  when  a 

14 


HYDATINA  SEUTA  (Rotifera,  Hudson 
and  Gosse).— a,  female,  dorsal 
view  ;  b,  male,  ditto. 


158 


A    COURSE   ON  ZOOLOGY. 


proper  degree  of  moisture  is  restored  to  them,  they 
again  become  endowed  with  the  functions  of  life. 

PARASITIC    WORMS    OR   HELMINTHES. 

Under  this  heading  are  classed  the  intestinal  worms 
formerly  considered  as  zoophytes,  but  which  certainly 
present  much  greater  analogies  with  the  anarthropoda. 
Their  bodies  are  composed  of  rings,  or  rather  segments, 
arranged  in  linear  scries.  They  have  no  organs  of 

FIG.  91. 


TAPE-WORM. 

locomotion,  and  sometimes  no  digestive  apparatus,  in 
the  latter  cases  they  absorb  through  the  skin  the  juices 
with  which  they  nourish  themselves  ;  they  also  respire 
by  the  skin,  for  there  is  no  special  respiratory  apparatus. 
Intestinal  worms  are  divided  into  three  classes: 

1.  Ribbon-like  worms,  or  cestoidea. 

2.  Round  worms,  or  nematoidea. 

3.  Flat  worms,  or  trematoidea. 


THE    TAPE-WORM.  159 

1.  The  cestoidea,  which  include  the  taenise  or  tape- 
worms and  the  bothriocephalus,  may  in  the  adult  stage 
reach  a  very  great  length,  at  the  same  time  keeping  a 
very  narrow  width.  Thus  the  taenia  solium,  the  common 
tape-worm,  is  sometimes  a  hundred  yards  in  length;  it 
then  presents  the  appearance  of  a  long  ribbon  formed  of 
numerous  rectangular  segments,  somewhat  longer  than 
they  are  wide,  and  joined  end  to  end.  Each  of  these 
segments  contains  male  and  female  organs, 
and  may  be  considered  as  an  individual, 
while  the  whole  worm  is  regarded  as  a 
colony  of  individuals  arranged  in  a  chain. 

However  this  may  be,  the  first  segments 
are  much  smaller,  and  are  more  closely 
pressed  together,  forming  a  sort  of  neck, 
at  the  end  of  which  appears  what  is  called 
the  head,  a  small  swelling  that  is  not  as  HEAD  OF  TAPE. 
large  as  the  head  of  a  pin,  and  that  carries  WORM,  EN- 
a  double  crown  of  thirty-two  hooks  and  hJokJT'*,  «i£ 
four  suckers,  arranged  like  a  cross.  The  holes;  s,  first 
hooks  and  suckers  enable  the  creature  to  fix 
itself  firmly  to  the  walls  of  the  intestine  in  which  it  lives. 

The  taenia  has  no  digestive  apparatus.  The  only  ones 
of  its  organs  that  have  been  studied  with  definite  results 
are  those  of  the  sexual  apparatus.  A  large  number  of 
eggs  are  produced,  and  when  a  segment  is  ripe  it  be- 
comes detached  and  is  carried  out  of  the  intestine. 

We  have  said  that  the  tape-worm  lives  as  a  parasite 
in  the  intestines  of  man,  and  it  is  by  eating  measly  pork 
that  man  acquires  the  unwelcome  guest.  In  order  to 
understand  this  indirect  transmission,  we  must  under- 
stand the  mode  of  development  of  the  creature,  which 
undergoes  metamorphoses  that  are  quite  complicated. 


160 


A   COURSE   ON   ZOOLOGY. 


The  eggs,  after  having  been  expelled  from  the  intes- 
tine with  the  matured  segment,  are  carried  by  the  rains 
into  dung-hills  and  feeding-troughs,  where  they  are  swal- 
lowed by  the  pig,  which  animal  we  know  is  not  delicate 
in  the  selection  of  its  food.  There  the  egg,  which  had 
begun  to  develop,  gives  birth  to  a  sort  of  larva  having 

six  little  hooks.    By  the  aid  of 
Fio.  93.  these  hooks  the  embryo  per- 

forates the  intestinal  wall  of 
the  pig,  and  migrates  into  the 
muscles  and  cellular  tissue ; 
hereitbecomesencysted, — that 
is,  completely  enveloped  by  a 
membrane.  It  loses  its  hooks, 
but  soon  on  the  wall  of  the  cyst 
BLADDER-WORM.  appears  a  little  bud,  which  is  a 

head  with  hooks  and  suckers, 

and  there  thus  exist  in  the  flesh  of  such  pork  little  sacs 
or  cysts  containing  a  stalked  head  fixed  to  the  wall  of 
the  sac. 

This  form  of  the  tape-worm  is  called  the  cysticercus  or 
bladder-worm.  It  remains  in  its  fleshy  enclosure  without 
further  development ;  but  when  the  pig  is  killed  and  its 
flesh  eaten  by  man,  the  cysticercus  arrives  in  new  sur- 
roundings, throws  off  its  envelope,  fixes  itself  to  the 
intestine  by  its  head  and  hooks,  and  in  a  few  weeks 
produces  a  long  chain  of  joints.  The  creature  is  now  an 
adult. 

Here,  then,  is  a  parasite  that  to  attain  complete  ma- 
turity must  pass  through  two  different  stages  in  two 
different  animals.  This  mode  of  development  is  quite 
frequent  in  animal  parasites.  For  the  development  of 
each  of  these  forms,  embryonic  and  adult,  a  particular 


PARASITIC   WORMS.  161 

field  is  required.     The  process'  is  parasitic  transmigra- 
tion. 

2.  Nematoidea. — The  parasitic  worms  of  this  class  are 
more  or  less  thread-like. 

The  hair-worm  or  dracunculus  is  an  example.  This 
is  a  sort  of  long  thread-like  creature  which  penetrates 
under  the  skin,  and  produces  symptoms  of  less  or  greater 
gravity.  It  is  viviparous,  and  in  this  respect  resembles 
the  trichina  spiralis,  a  small  filiform  worm  that  produces 
the  disease  known  as  trichinosis,  that  is  communicated 
to  man  by  the  pig.  In  the  embryonic  state  the  trichina 
inhabits  the  muscles  of  the  pig,  so  much  so  that  the  in- 
fected flesh  is  literally  crowded  with  them.  Under  the 
microscope  the  parasite  appears  as  a  little  worm  coiled  in 
a  spiral  in  a  little  sac  or  cyst.  When  man  eats  such  flesh 
the  young  trichinae  are  developed  in  his  intestine,  and 
thousands  of  these  creatures  perforate  the  intestines  and 
pass  into  the  muscles.  Trichinosis  is  a  dangerous  disease, 
very  common  in  sections  of  countries  where  raw  pork  is 
eaten.  The  trichina  is  destroyed  by  thorough  cooking. 

The  other  nematoidea  are  all  oviparous.  Such  are,  for 
example,  the  pin-worms  or  seat-worms  of  children,  the 
oxyurus  vermicularis,  that  inhabits  the  rectum,  the  as- 
carides  that  live  in  the  small  intestine,  etc. 

3.  Trematoidea. — Underthis  title  are  considered  those 
worms  that  are  flattened  in  the  form  of  a  heart  or  leaf, 
and  that  are  generally  known  as  gourd-worms.     Their 
digestive  apparatus  usually  consists  of  two  branching 
tubes.     Two  suckers,  one  oral  and  one  ventral,  serve  to 
fix  the  creature  in  position.    These  parasites  pass  through 
various  stages  in  the  course  of  their  development.     They 
have  been  found  in  the  kidneys  and  in  the  liver  of  man, 
and  they  are  not  uncommon  in  cattle. 

I  14* 


]  62  A   COURSE   ON    ZOOLOGY. 

It  must  not  be  thought  that  worms  are  the  only 
species  that  live  as  parasites.  Parasitic  animals  are 
found  among  insects,  such  as  lice,  fleas,  etc. ;  among 
spiders,  as  the  ascaris  or  itch  parasite ;  and  among  crus- 
taceans. Parasitism  is  only  the  condition  of  a  certain 
number  of  creatures  incapable  of  supplying  their  own 
wants.  We  will  return  to  the  subject  when  considering 
animals  injurious  to  man. 

We  will  now  resume  the  generalities  on  the  organiza- 
tion of  annelida  in  the  following  table,  which  indicates 
the  different  groups : 


NERVOUS 
SYSTEM. 


(  ganglionic ;  well  developed.  Annelides. 


t  rudimentary 


non -parasitic :  month  furnished 

with  vibratile  cilia.  Rotatoria. 

f  ribbon-like.        Cestoidea. 
parasitic  ;  no   I  cylindrical.         Nematoidea. 
cilia;  3  forms      flattened.  Trematoidea. 


CHAPTER   XVIII. 
General   Ideas    concerning  Mollusks. 

THE  mollusks  have  no  internal  skeleton  like  the  ver- 
tebrates, nor  an  external  skeleton  formed  by  a  harden- 
ing of  the  skin,  as  in  a  large  number  of  articulates 
and  arthropods;  this  is  indicated  by  the  name  mollusk, 
which  means  soft  animals.  Most  of  them  are,  however, 
provided  with  a  shell,  which  serves  for  protection,  and 
represents  a  sort  of  skeleton. 

The  shell  is  cither  univalve  or  bivalve  as  it  is  composed 
of  one  or  two  pieces.  Whatever  its  form  may  be,  it  is 
always  a  product  of  secretion  of  the  skin. 


GENERAL    IDEAS    CONCERNING    MOLLUSKS.  163 

The  skin  forms  around  the  bodies  of  mollusks  an 
envelope  that  is  usually  largely  extended  at  one  part, 
and  folded  on  itself,  and  this  arrangement  is  called  the 
mantle. 

When  we  examine  a  bivalve  shell,  that  of  the  oyster, 
for  example,  we  find  that  each  half  is  formed  of  a  num- 
ber of  layers,  which  are  wider  as  they  are  closer  to  the 
interior.  The  external  layers  are  the  older,  and  as  the 
oyster  grows  larger  it  extends  the  internal  surface  of  its 
dwelling.  In  the  shell  of  the  snail,  which  is  univalve, 
the  effect  of  growth  is  to  increase  the  number  of  turns 
of  the  spiral.  When  the  shell  is  bivalve  the  two  halves 
are  held  apart  by  the  action  of  the  ligaments  that  form 
the  hinge  ;  they  are  tightly  pressed  together  by  the  con- 
traction of  two  muscles.  The  only  opening  of  univalve 
shells  is  generally  closed  by  a  small  mobile  disk  called 
the  operculum. 

In  certain  species  the  shell  is  so  small  that  it  can  be 
of  no  apparent  use.  In  others  there  is  no  external 
shell,  but  there  is  then  often  an  internal  calcareous  piece 
analogous  to  what  is  called  cuttle-fish  bone. 

Most  of  the  mollusks  have  the  power  of  movement ; 
a  large  number  of  them,  however,  live  fixed  to  rocks  and 
other  submerged  masses,  to  which  they  adhere  sometimes 
by  the  aid  of  a  fleshy  foot,  sometimes  by  filaments  that 
develop  on  the  external  surface  of  the  shell. 

The  organs  that  serve  the  functions  of  digestion,  cir- 
culation, respiration,  and  relation,  show  in  the  mollusks 
a  great  variety  of  form.  Yet  certain  peculiarities  are 
sufficiently  characteristic  to  be  mentioned. 

The  digestive  tube,  composed  of  a  canal  having  more 
or  less  numerous  pockets  in  its  course,  according  to  the 
species,  is  always  arranged  somewhat  or  entirely  in  the 


164 


A  COURSE  ON  ZOOLOGY. 


PIG.  94. 


form  of  a  U, — that  is,  the  two  extreme  orifices  are  quite 
close  to  each  other.  Besides,  the  relations  of  the  intes- 
tine with  the  heart  are  very  intimate,  and  often  the 
heart  straddles  the  intestine.  The  liver  is  very  large. 

The  heart  is  arterial, — that  is,  it  is  traversed  by  red 
blood,  and  there  are  arterial  vessels  and  venous  vessels. 
However,  there  are  no  capillaries,  these  being  replaced 
by  lacunae  between  the  organs  and  in  the  muscles. 

The  respiratory  organs  differ  both  in  their  structure, 
their  form,  and  their  arrangement.  We  must  note  in  a 
general  manner  that  they  are  placed  under  the  mantle, 
which  forms  a  respiratory  chamber  designed  to  contain 
either  air  or  water.  Ordinarily  respiration  is  aquatic, 
and  is  effected  by  gills  usually  located 
on  the  exterior;  however, in  certain  mol- 
lusks,  naked  snails  for  example,  it  is  aerial, 
and  has  for  its  seat  an  interior  cavity 
that  has  been  compared  to  the  lungs.  It 
is  a  curious  fact  that  among  the  pul- 
monary mollusks  several  species  are 
aquatic.  The  latter,  like  the  correspond- 
ing members  of  the  insect  class,  are 
obliged  to  seek  frequently  the  surface 
of  the  water  for  a  supply  of  air. 

The  nervous  system  always  presents 
an  cesophageal  collar,  joining  the  cerebral 
ganglions  with  those  situated  in  the  foot, 
in  the  base  of  the  gills,  or  in  the  mouth  ; 
but  the  latter  ganglia  are  not  united  in  a 
chain  or  linear  series  as  in  the  ariarthropods. 
All  mollusks  are  oviparous. 

We  cannot  go  into  detail  on  the  classification  of  mol- 
lusks. The  division  includes  six  orders,  of  which  only 


NERVOUS  SYSTEM 
OF  A  MOLLUSK.— 
1,  cesophageal 
chain  ;  2  and  3, 
ganglia. 


CEPHALOPODS.  165 

three — the  cephalopods,  the  gasteropods,  and  the  aceph- 
alans — are  worthy  of  our  special  notice. 

CEPHALOPODS. 

Cephalopods  have  a  well-defined  head,  generally  sur- 
rounded by  a  number  of  tentacles,  which  are  large, 
fleshy  arms,  serving  both  for  locomotion  and  prehension. 

FIG.  95. 


COMMON  OCTOPUS  ( Octopus  vulgaris). 

In  these  animals,  which  are  the  most  perfect  of  the 
mollusks,  two  large,  contractile  venous  sinuses  force  the 
blood  into  the  gills,  which  occupy  the  bottom  of  the 
respiratory  chamber  formed  by  the  mantle.  In  the 
calamary  or  squid,  the  cuttle-fish,  the  poulp,  etc.,  there 
is  near  the  anus  the  orifice  of  a  gland  called  the  "  ink- 


166  A    COURSE   ON    ZOOLOGY. 

bag,"   that   produces   a   black   liquid   from   which   the 
artists'  color,  sepia,  was  formerly  prepared. 

Cephalopods  have  been  classified  in  two  groups,  ac- 
cording to  the  number  of  gills.  The  dibranchial  are 
those  that  have  two  gills,  like  the  argonaut,  the  sepia, 
and  the  squid.  The  tetrabranchial  have  four  gills,  arid  are 
now  represented  only  by  the  genus  nautilus,  which  was 


FIG. 


CUTTLE-FISH  (Sepia  officinalis),  swimming  and  at  rest. 


very  abundant  in  geologic  ages ;  the  ammonites,  now 
found  only  as  fossils,  belong  to  this  group. 

Cephalopods  all  live  in  the  sea ;  we  can  mention  only 
the  squids  and  the  cuttle-fish. 

Squids  are  abundant  on  the  Atlantic  coast.  By  the 
aid  of  their  eight  strong  arms,  which  are  furnished  with 
suckers,  they  swim  in  the  water  or  climb  over  the  rocks. 
Those  which  are  seen  usually  are  rather  small,  but  out 


GASTEROPODS.  167 

at  sea  some  have  been  encountered  that  weighed  as  much 
as  two  tons.  In  Greece  and  in  Italy  the  flesh  of  squids 
is  eaten,  but  it  is  very  tough  and  dry. 

Cuttle-fish  are  common  in  all  seas ;  they  are  very 
voracious,  living  on  fish  and  crustaceans.  Like  many 
other  cephalopods,  they  have  the  power  of  throwing 
out  an  inky  liquid  that  darkens  the  water  and  allows 
them  to  escape  from  pursuers.  The  cuttle-fish  bones  of 
the  drug-store  are  the  calcareous  remains  of  the  bodies 
of  the  cuttle-fish ;  they  are  used  as  polishing  stones, 
and  are  given  to  cage-birds,  both  to  furnish  calcareous 
matter  and  to  enable  them  to  sharpen  their  beaks. 

GASTEROPODS. 

The  gasteropods  climb  about  by  the  aid  of  a  fleshy 
disk  with  which  the  inferior  surface  of  the  body  is  pro- 
vided, and  which  sometimes  has  the  form  of  a  fin.  The 
head  is  always  visible  outside  of  the  mantle,  and  has 
above  the  mouth  tentacles  that  appear  to  be  organs  of 
sensation ;  these  tentacles  are  sometimes  furnished  with 
eyes. 

Some  gasteropods  are  naked,  but  most  of  them  have 
a  univalve  shell  in  which  the  body  may  be  more  or  less 
completely  enclosed.  The  form  of  this  shell  presents 
infinite  variation :  sometimes  it  is  a  straight  cone,  but 
more  often  it  is  curved  and  rolled  up  on  itself  several 
times,  forming  a  spiral.  It  is  said  to  be  discoid  when 
the  spiral  is  in  one  plane,  and  turbinated  when  the  coils 
are  piled  on  one  another.  In  some  cases  the  coils  are 
independent  and  not  contiguous ;  but  in  most  cases  they 
are  exactly  fitted  one  on  another,  so  that  the  central 
axis  is  occupied  by  a  sort  of  twisted  column. 

The  species  of  gasteropods  are  very  numerous.    Nearly 


168 


A    COURSE   ON    ZOOLOGY. 


all  are  aquatic,  some  living  in  fresh,  others  in  salt  water. 
In  some  the  respiratory  organs  are  analogous  to  lungs ; 
in  others   they   are   gills,   which   are 
situated    sometimes   internally,  some- 
times externally. 

Among  the  gasteropods  having 
lungs,  the  more  important  are  the 
edible  snails  or  helixes,  the  slugs  or 
naked  snails,  and  the  various  pond 
snails.  Of  the  latter,  two  very  small 
species,  the  limnsea  and  the  planorbis, 
abound  in  stagnant  waters ;  the  former 
have  conical  shells,  while  those  of  the 
latter  are  discoid.  Edible  snails  are 
found  in  all  quarters  of  the  globe ; 
they  live  on  leaves  and  fruits,  and, 
although  their  mouth  has  but  a  single 
tooth,  they  can  do  great  damage  in 
vegetable  gardens.  Their  use  as  food 
was  for  a  long  time  restricted  to  very 
limited  districts,  but  they  are  now  much  sought  for 
the  table.  The  most  highly-esteemed  species  is  the 
vineyard  snail,  having  a  russet  color,  with  paler  stripes, 
and  commonly  found  in  vineyards.  The  slugs  having 
a  viscous  skin  and  a  repulsive  appearance  are  quite  as 
destructive  as  the  edible  snails.  The  most  common 
species  are  the  red  snail,  found  in  the  woods,  the  cellar 
snail,  and  the  black  snail. 

The  gasteropods  having  gills  can  only  be  mentioned  for 
the  varied  and  often  very  singular  appearance  of  their 
shells.  Among  them  may  be  named  the  top,  the  bubble, 
pouch,  boatman,  hatchet,  dolphin,  all  named  from  their 
curious  forms,  and  the  various  limpets,  Under  the  name 


ac 

SECTION  OF  TRITON- 
SHELL  (after  Owen). 
— oc,  notch  for  si- 
phon ;  c,  axis  or  col- 

umella. 


GASTEROPODS.  169 

cowry,  a  small  species  of  porcelain  shell  is  used  in  Africa 
and  India  as  money.  Some  shells  are  made  up  of  layers 
having  different  colors,  and  are  used  to  make  large 
cameos.  Others,  whose  interiors  are  lined  with  a  layer 
having  brilliant  pearly  reflections,  furnish  the  mother- 
of-pearl  of  commerce.  It  is  probable  that  the  famous 
Tyrian  purple  was  manufactured  from  certain  of  these 
colored  shells. 


EDIBLE  SNAIL  (the  shell  has  been  removed,  and  the  animal  opened  through 
the  back).— t,  tentacles;  ph,  oasophagus  ;  mt,  muscles  of  the  tentacles;  n, 
oesophageal  ganglia ;  gs,  salivary  gland ;  e,  stomach  ;  ao,  anterior  aorta ;  m, 
mucous  gland ;  pp',  lung  and  its  orifice,  a ;  i,  intestine ;  o,  auricle ;  v,  ventri- 
cle ;  F,  liver ;  p,  foot ;  r,  oviduct. 

To  study  the  internal  organization  of  the  gasteropods 
we  may  select  the  common  edible  snail.  After  having 
removed  the  shell  and  cut  the  creature  open,  we  find  a 
stomach  with  salivary  glands,  and  a  large  liver  occupy- 
ing the  posterior  portion.  The  heart  is  to  the  left,  and 
may  be  seen  to  beat  by  cutting  a  rather  large  window 
in  the  shell  of  a  snail.  The  egg-passage  or  oviduct  may 
H  15 


170  A    COURSE   ON    ZOOLOGY. 

be  distinguished  by  its  twisted  condition.  The  respira- 
tory apparatus  is  a  sort  of  lung  consisting  of  a  respira- 
tory chamber  whose  ceiling  is  traversed  by  canals  filled 
with  blood. 

ACEPHALANS. 

The  acephalans  have  no  distinct  heads ;  the  mouth  is 
always  hidden  at  the  bottom  of  the  mantle  or  in  its 
folds ;  the  gills  are  striated  leaves ;  the  lower  part  of  the 
body  is  ordinarily  elongated  into  a  sort  of  fleshy  foot. 
The  shell  consists  of  two  valves  articulated  by  a  hinge. 
All  these  mollusks  are  aquatic,  and  most  of  them  inhabit 

FIG.  99. 


DIAGRAM  OF  INTERNAL  STRUCTURE  OF  OYSTER  (the  dorsal  surface  is  down- 
ward, the  anterior  or  head  end  to  the  left). — a,  region  where  water  enters 
and  leaves  the  animal ;  the  dark  lines  indicate  where  one  mantle-flap  has 
been  cut  away  to  expose  the  other  structures ;  6,  gills ;  c,  margin  of  one  of 
the  mantle-folds ;  d,  anterior  part  of  hinge ;  e,  hood  over  mouth ;/,  position 
of  mouth ;  gh,  labial  palps ;  i,  end  of  intestine ;  I,  the  closing  muscle  of 
the  shell ;  m,  position  of  the  heart. 


the  sea.  Many,  like  the  oyster,  remain  firmly  fixed  on  a 
rocky  moorage  ;  others  drag  themselves  over  the  muddy 
bottom.  The  class  includes  an  immense  variety  of  species, 


ACEPHALANS.  171 

among  which  we  will  only  mention  the  oyster,  clam, 
mussel,  and  teredo. 

Oysters  live  in  salt  and  brackish  water,  not  far  from 
shore,  and  at  but  little  depth.  They  nourish  especially 
in  calm  bays  and  the  mouths  of  rivers.  The  often  very 
extensive  colonies  that  they  form  on  rocks  are  called 
oyster-beds  or  banks,  and  from  these  they  are  taken  by 
the  oyster  fisherman  by  the  aid  of  scoops  or  drags. 

The  pearl  oyster  is  celebrated  for  the  pearly  lining  of 
its  shell  and  for  the  pearls  found  enclosed  between  the 
shells.  The  pearls  are  produced  by  the  ordinary  shell- 
excreting  glands  of  the  oyster,  excited  by  the  presence 
of  a  foreign  body,  usually  a  grain  of  sand.  Pearl-fishing  is 
carried  on  principally  on  the  shores  of  Ceylon,  but  there 
are  also  large  beds  of  pearl  oysters  in  the  Persian  Gulf, 
in  the  Gulf  of  Mexico,  and  on  the  shores  of  Australia. 

Mussels  are  found  on  rocks  near  the  shore.  They  are 
much  used  as  food,  but  some  species  appear  to  be  poison- 
ous. Some  species  inhabit  fresh  waters,  both  rivers  and 
ponds,  and  there  is  a  marine  species  whose  shell  is  prized 
for  its  great  lustre,  and  which  often  contains  pearls. 

The  teredos  are,  unfortunately,  too  well  known  by  the 
injuries  they  cause  to  wooden  ships  and  naval  construc- 
tions. Several  times  they  have  nearly  caused  the  sub- 
mersion of  Holland  by  perforating  the  dikes  that  pro- 
tect that  country  from  the  sea.  The  teredo  uses  its  shell 
as  an  auger  in  driving  forward  its  tunnel. 

The  name  molluscoid  is  applied  to  certain  creatures 
that  are  analogous  to  the  acephalous  mollusks ;  they  are 
classified  as  tunicata  and  polyzoa. 

The  tunicata  have  no  shells,  but  the  mantle  that 
envelops  the  body  is  thickened,  sometimes  being  like 
leather.  They  live  in  the  sea,  and  have  been  divided 


172  A   COURSE   ON    ZOOLOGY. 

into  two  groups,  the  salpae  and  the  ascidians.  Some  of 
the  latter  are  simple,  some  are  compound, — that  is.  they 
are  found  singly  or  in  numerous  colonies.  Their  form, 
generally  speaking,  is  that  of  a  tube  having  two  orifices 
corresponding  to  the  two  extremities  of  the  alimentary 
canal.  They  respire  by  means  of  an  apparatus  like 

FIG.  100. 


TEREDO  IN  ITS  BOEING. 

internal  gills.  The  salpse  have  alternate  generation.  A 
single  individual  produces  a  chain-like  colony,  and  each 
of  these  produces  a  single  detached  individual  that  in 
its  turn  produces  a  chain  of  successors. 

The  polyzoans,  and  ascidians,  are  aquatic  creatures, 
some  living  in  fresh  water,  others  in  the  sea.  They  have 
vibratile  tentacles,  and  usually  dwell  in  colonies. 


CHAPTER  XIX. 
Radiates. 

UNDER  the  name  radiates  are  grouped  a  large  number 
of  lower  creatures  whose  bodies  present,  in  a  more  or 
less  apparent  manner,  the  form  of  a  star ;  some,  how- 
ever, are  globe-shaped,  some  cylindrical. 


RADIATES. 


173 


The  radiates  constitute  the  greater  part  of  the  group 
of  beings  known  as  zoophytes;  they  have  been  divided 
into  several  classes,  the  more  important  of  which  are 
the  echinodermata,  the  acalepha,  the  corals,  and  the 
sponges. 

We  will  examine  a  few  types  adapted  to  give  us  gen- 
eral idea's  concerning  these  classes. 

To  the  echinodermata  belong  the  sea-urchins  and  the 

star-fish. 

FIG.  101. 


SEA-URCHIN. 

The  sea-urchins  have  a  sensibly  rounded  form,  the 
body  being  protected  by  a  calcareous  envelope  that  is 
studded  with  thorns.  These  creatures  are  found  in  all 
seas,  and  form  a  large  number  of  species.  The  common 
sea-urchin  is  about  as  large  as  a  fairly  large  apple ;  it 


174 


A  COURSE  ON  ZOOLOGY. 


has  violet  spines,  is  very  abundant,  and  is  used  as  food 

in  some  maritime  localities. 

The  sea-urchin  has  a  mouth  provided  with  calcareous 

joints    shaped    like 

FIG.  102.  little  pyramids,  the 

summits  converging 
to  a  point.  These 
form  a  sort  of  teeth, 
and,  being  put  in 
movement  by  the 
action  of  muscles, 
serve  to  tear  up  the 
food.  The  solid 
frame  -  work  has 
been  called  Aris- 
totle's lantern.  The 
digestive  tube  is 
well  developed  and 
tortuous. 

The  asterias  or 
star -fish  owes  its 
name  to  the  form 
of  its  body,  which  is 
divided  into  five  or 
ten  rays.  In  some 
species  these  rays 
are  subdivided  indef- 
initely, and  form  a 
sort  of  tangled  hair. 


UNDER  SIDE  OF  A  STAR-FISH  (the  rays  are  cut 
open  to  show  the  organs).— b,  mouth ;  d,  ap- 
pendages of  the  intestine ;  e,  stomach  ;  an, 
cesophageal  ganglia ;  av,  annular  canal, — mad- 
reporic  (perforated)  plate ;  t,  open  covering. 


Sometimes  these  star  fish  are  found  in  such  numbers  that 
they  are  used  as  manure  for  the  fields.  Like  the  sea- 
urchins,  they  are  very  voracious  ;  the  mouth  is  in  the 
central  portion,  and  leads  by  a  short  oasophagus  into  an 


RADIATES. 


175 


FIG.  103. 


AURELIA  AURITA  (reduced). 


annular  stomach,  which  sends  an  intestinal  branch  into 
each  arm.  These  tubes  are  accompanied  by  yellow 
bodies  that  surround  them,  and  constitute  the  liver. 

The  acalepha  include  many  species  of  medusae  or  jelly- 
fish. These  are  beings 
of  a  gelatinous  con- 
sistence, having  vari- 
ous colors,  and  bodies 
formed  like  a  flattened 
disk  or  a  rounded  bell. 
The  central  mouth  is 
often  surrounded  by 
long  tentacles,  that 
float  in  the  water.  The 
digestive  apparatus  is 
composed  of  tubes 

more  or  less  ramified  in  the  centre  of  the  gelatinous 
mass.  This  latter  character  is  common  to  the  acalepha 
and  the  corals,  and  leads  to  the  frequent  union  of  the 
two  groups  under  the  title  coelentera. 

The  medusa  present  brilliant  colors  while  floating  in 
the  sea,  but  soon  fade  when  they  are  removed  from  the 
water.  When  they  are  touched,  most  of  them  produce 
on  contact  with  the  skin  an  itching  like  that  caused  by 
the  sting  of  a  nettle.  For  this  reason  they  are  sometimes 
known  as  sea-nettles. 

In  the  course  of  their  development  many  of  the  me- 
dusae pass  through  a  series  of  intermediate  states,  and 
furnish  good  examples  of  alternate  generation.  The 
medusa  produces  a  ciliated  larva  which  fixes  itself,  and 
at  the  same  time  its  borders  become  lined  with  tentacles. 
When  these  latter  are  acquired,  the  young  creature  re- 
sembles a  goblet  with  a  fringed  border.  Then  it  under- 


176  A   COURSE   ON   ZOOLOGY. 

goes  new  transformations  ;  series  of  annular  contractions 
appear  a  certain  distance  behind  the  circle  of  tentacles  ; 
gradually  these  contractions  become  more  and  more 
prominent,  and  the  appearance  of  the  animal  is  like  that 
of  a  number  of  superposed  disks.  The  borders  of  the 
disks  become  fringed  in  their  turn ;  the  contractions  or 
strangulations  between  them  increase,  and,  finally,  the 
mass  breaks  up  into  as  many  little  medusae  as  there  are 

FIG.  104. 


LIFE-HISTORY  OF  THE  COMMON  JELLY-FISH.— 1,  free-swimming  embryo  (pla- 
nula);  2-6,  the  embryo  fixed,  developing  into  a  "hydra-tuba,"  which  (7-8) 
divides  transversely  into  a  pile  of  individuals;  these  in  turn  (9)  are  liber- 
ated and  grow  (10-11)  into  jelly-fish.  (From  Haeckel.) 

disks ;  each  of  these  lives  freely,  grows,  and  acquires  the 
full  and  definite  form,  .and  gives  birth  to  ciliated  larvsB. 
Then  the  cycle  of  alternate  generation  recommences  in 
the  same  manner  and  in  the  same  order. 

The  coralligena  include  creatures  that  are  often  also 
called  polyps,  because  of  the  numerous  processes  or  ten- 
tacles that  surround  their  mouths.  Nearly  all  these  pass 
their  existence  fixed  upon  some  foreign  body.  They 
reproduce  their  species  by  eggs  and  by  buds,  each  of  the 


RADIATES. 


177 


latter  becoming  a  perfect  creature,  yet  remaining  adher- 
ent to  the  original  polyp.  There  thus  result  polyparies 
or  coral  manses, — masses  consisting  of  distinct  individ- 
uals, living  with  a  collective  existence  either  by  having 
one  common  digestive  tube  or  by  vascular  intercom- 
munication. Some  of  these  are  quite  soft,  such  as  the 
sea-anemones,  so  named  on  account  of  their  variously- 

FIG.  105. 


A,  Anemonia  sulcata  ;  B,  Cerianthus  membranaceus ;  C,  Bunodes  gemmaceus 
(closed) ;  D,  the  same  (open). 

colored  and  numerous  tentacles,  that,  when  spread  out, 
resemble  a  flower  in  full  bloom.  However,  in  a  large 
number  of  these  creatures  the  soft  parts  are  sustained 
by  a  hard  calcareous  skeleton,  constituting  the  polypary 
or  coral.  In  the  madrepores  this  skeleton  is  developed 
in  the  form  of  a  cup,  whose  walls  carry  radiating  par- 


178 


A  COURSE  ON  ZOOLOGY. 


titions.  These  partitions  correspond  in  number  to  the 
tentacles  of  the  polyp.  Since  the  corals  multiply  by 
breeding,  and  remain  united  in  colonies,  large  polyparies 
are  often  found,  consisting  of  as  many  little  cups  as  there 
are  creatures  in  the  polypary.  The  form  of  the  mass 
differs  according  to  the  species,  but,  since  the  breeding 
takes  place  in  the  same  manner  in  each  species,  it  follows 
that  the  form  of  the  coral  mass  is  also  constant  for  each. 

FIG.  106. 


A,  branch  of  dendrophyllia ;  B,  part  of  a  stock  of  red  coral,  with  (a)  fully 
extended  polyp,  and  (6,  b)  two  polyps  partly  extended. 

Most  of  these  creatures  dwell  in  the  sea,  but  there  are 
a  few  species  found  in  fresh  water.  The  calcareous 
polyps  grow  only  in  warm  seas,  and  there  increase  in 
such  abundance  that  they  form  islands  of  vast  extent. 
The  well-established  origin  of  these  islands  and  the 


RADIATES.  179 

enormous  quantities  of  fossil  coral  that  are  met  with  in 
calcareous  rocks  have  led  to  the  belief  that  the  pro- 
ductions of  these  zoophytes  form  a  large  portion  of  the 
mass  of  our  continents,  and  that  these  small  beings  may 
modify  the  outlines  of  the  earth's  crust  in  a  rapid  and 
remarkable  manner.  If  we  may  judge  by  the  results  of 
investigations  made  during  less  than  a  century  just  past, 
we  are  justified  in  the  conclusion  that,  in  a  time  rela- 
tively short  for  geological  change,  the  greater  number 
of  the  islands  of  Oceanica  will  be  united  together. 

Eed  coral  is  the  earthy  axis  of  a  polyp  that  grows  in 
abundance  in  the  Persian  Gulf,  the  Red  Sea,  and  various 
parts  of  the  Mediterranean,  such  as  the  Straits  of  Mes- 
sina, off  the  coasts  of  Sardinia,  Tunis,  and  Algeria.  The 
stem  or  axis  adheres  to  submarine  rocks,  generally 
has  a  beautiful  red  color,  and  the  form  of  a  little  tree 
without  leaves  or  small  branches,  and  a  height  vary- 
ing between  six  and  twenty-five  inches.  A  single  polyp 
like  that  shown  in  Fig.  106  is  the  starting-point  of  the 
coral  stem  represented  alongside  of  it.  On  the  smaller 
branches  of  the  stem  are  seen  young  individuals,  whose 
development  will  produce  new  branchings.  This  method 
of  development  is  quite  analogous  to  that  of  vegetables. 

The  class  of  porifera  includes  the  sponges,  beings 
formed  of  a  gelatinous  mass,  supported  by  a  solid  frame- 
work of  variable  composition.  Sometimes  this  frame- 
work is  composed  of  long  silicious  needles  interlaced  and 
resembling  spun  glass ;  sometimes  it  consists  of  calca- 
reous spiculae  or  of  horny  filaments.  The  common  sponge 
is  of  the  latter  variety,  and  it  is  the  horny  skeleton  that 
is  used.  The  holes  that  run  through  it  in  all  directions 
are  the  canals  through  which  water  circulates  during  the 
life  of  the  creature. 


180 


A  COURSE  ON  ZOOLOGY. 


Like  the  corals,  sponges  fix  themselves  on  submarine 
rocks;  they  are  found  in  all  seas,  but  those  from  the  Medi- 
terranean, and  particularly  those  of  the  Archipelago,  are 
most  esteemed.  The  preparation  of  the  sponges  is  very 
simple,  consisting  of  washing  them  many  times  in  fre- 
quently renewed  fresh  water.  In  this  manner  they  are 
freed  from  their  gelatinous  envelopes  and  the  foreign 
matters  distributed  through  their  tissue. 


CHAPTER  XX. 
Protozoa — Infusoria — Microbes. 

THE  protozoa  are  animals  of  extremely  simple  organ- 
ization, and  most  generally  of  a  microscopic  size.     They 


FIG.  107. 


FIG.  108. 


PAKAMECIUM  AUEELIA.     COLPODA. 


STENTOR.     BURSARIA  VORTICELLA. 


INFUSORIA.  181 

are  subdivided  in   two  principal  groups,  infusoria  and 
rhizopods. 

The  infusoria  are  little  masses  of  definite  form,  com- 
posed of  protoplasm  or  gelatinous  living  matter.  They 
are  covered  with  an  envelope  carrying  vibratile  cilia.  Of 
all  the  protozoa  they  are  the  most  highly  organized 
beings,  for  they 

possess  a  digestive  FIG.  109. 

apparatus  with 
two  orifices,  and 
in  their  mass  we 
can  distinguish 
vacuoles  or  clear 
spaces,  and  a  pul- 
satile  vesicle  which 
probably  serves  for  the  digestion  and  circulation  of  a 
nutritive  liquid.  These  little  beings  have  been  named 
infusoria-  because  their  first  observers  found  them  in 
putrid  infusions  of  vegetables  ;  they  are  especially  abun- 
dant in  stagnant  waters. 

Their  reproduction  takes  place  by  eggs  and  also  by 
scission,  which  is  simply  a  division  of  the  creature  in 
two. 

They  are  divided  into  several  groups,  according  to  the 
arrangement  of  the  cilia  and  the  general  form  of  the 
body. 

1.  The  cilia  may  be  arranged  in  longitudinal  lines 
covering  the  entire  body  excepting  around  the  mouth. 
Among   the   forms  of   this  kind  are  paramecium  and 
opalina, 

2.  The  body  may  be  covered  with  cilia,  with  long  rigid 
hairs  around  the  mouth.     The  stentor  and  bursaria  are 
examples. 

16 


182 


A   COURSE   ON    ZOOLOGY. 


3.  The  body  has  a  convex  dorsal  surface  and  a  flat 
ventral  surface  carrying  cilia;  the  back  is  often  hard- 
ened so  that  the  creature  much  resembles  a  minute  crus- 
tacean ;  examples  are  euplotes  and  oxytricha. 


Fia.  110. 


VORTICELLA  CONVALLARIA. 


LACRYMARIA  PROTEUS. 


4.  In  this  class  the  body  is  usually  naked,  excepting  a 
girdle  of  elongated  cilia,  and  a  spiral  of  hairs  around  the 
mouth.  Examples  of  these  are  the  ophrydmm  and  the 
vorticella,  The  bodies  of  all  the  vorticellse  are  supported 
by  a  long  contractile  stalk.  When  this  is  contracted  the 
creature  looks  like  a  microscopic  flask ;  it  remains  at- 
tached to  a  plant,  awaiting  the  passage  of  some  desired 
prey ;  then  it  elongates  its  stalk  very  rapidly,  like  a 
liberated  spring. 

The  figures  on  pages  180,  181,  and  182  illustrate  the 
principal  forms  that  are  found  in  old  vegetable  infusions 
and  in  stagnant  water. 


FORAMINIFERA. 


183 


Closely  related  to  the  infusoria  are  the  foraminifera, 
minute  beings  whose  organization  is  still  more  simple 
than  that  of  the  former.  They  move  around  at  the 
bottom  of  fresh  and  salt  water,  and  their  bodies  consist 
simply  of  microscopic  masses  of  protoplasm  gifted  with 
the  power  of  movement,  and  called  sarcode.  Move- 
ment is  accomplished  by  more  or  less  numerous  and 
lengthy  expansions,  which  may  be  observed  to  project 
from  the  surface  of  the  body,  into  which  they  after- 
wards retract  and  disappear. 


AMCEBA.— 1,  amoeba,  with  blunt  processes,  nucleus,  nc,  contractile  vacuoles, 
vc,  food  vacuoles,  and  granules ;  2,  two  daughter-amoebae  ;  3,  amoeba  in  pro- 
cess of  dividing ;  4,  encysted  phase,  with  enclosed  diatoms,  etc.  (After 
Butschli  and  G.  B.  Howes.) 


Sometimes  the  sarcode  is  naked,  and  the  forms  are 
then  the  most  simple,  being  known  as  amceba3  and  pro- 
tamoeba3. 

Sometimes,  however,  the  sarcode  is  covered  with  a 
calcareous  envelope,  a  sort  of  carapace,  pierced  with  nu- 


184 


A    COURSE    ON    ZOOLOGY. 


FIG.  112.  merous  holes  through 

which     the    retractile 
may     is- 


expansions 
sue. 

The  shells  of  fora- 
mi  nifera  are  secreted 
by  the  sarcode,  but,  on 
account  of  their  min- 
eral nature,  they  are 
not  destroyed  with  the 
life  of  the  creature. 
The  microscopic  shells 
of  innumerable  beings 
of  this  kind  form  thick 
layers  of  sediment  on 
the  bottoms  of  certain 
seas.  It  has  been  cal- 
culated that  one  ounce 
of  sand  taken  in  front 

of  the   port  of  Gaeta  contains  about  one  and  a  half 

millions  of  such  calcareous  shells. 

FIG.  113. 


A  LIVING  FORAMINIFER  (Polystomelld 

strigillata). 


SHELLS  OF  VARIOUS  FORAMINIFERA. 


MICROBES.  185 

MICROBES. 

By  the  name  microbes  are  understood  beings  of  ex- 
ceeding smallness,  that  can  be  seen  only  by  the  aid  of 
powerful  microscopes ;  they  are  less  than  one-ten-thou- 
sandth of  an  inch  in  diameter,  but  their  number  is  so 
large  that  it  compensates  for  their  minute  size. 

These  beings  take  a  very  important  part  in  nature. 
In  particular,  they  appear  to  be  the  causes  of  all  the 
putrefactions  and  fermentations  with  which  we  are 
acquainted.  Besides,  many  of  them  live  as  parasites  in 
the  blood  or  in  the  organs  of  men  and  other  animals, 
and  by  their  presence  occasion  the  most  serious  diseases. 
It  is  now  proved  that  all  the  contagious  affections  are 
caused  by  microbes :  thus,  the  anthrax,  or  carbuncle, 
which  sometimes  decimates  cattle,  hydrophobia,  typhoid 
fever,  intermittent  fever,  scarlet  fever,  measles,  cholera, 
etc.,  are  due  to  the  presence  of  specific  microbes  in  the 
blood  or  in  some  part  of  the  organism.  It  is  impossible 
for  us  to  enter  into  minute  details  concerning  these 
little  creatures,  and  we  can  only  indicate  their  more 
common  forms.  In  this  respect  they  may  be  divided 
into  two  classes :  the  ones  called  monads  are  globular ; 
the  others  are  filiform.  The  latter  are  sometimes 
straight,  as  the  bacterium  of  carbuncle,  sometimes  un- 
dulating, as  the  vibrios,  sometimes  curled  in  a  spiral,  as 
the  spirillum. 

The  bacteria  of  malignant  anthrax,  which  we  will 
take  as  an  example,  consist  of  rigid,  straight,  cylindri- 
cal filaments,  at  the  most  about  one  twenty-five-hun- 
dredth part  of  an  inch  in  length.  These  filaments  are 
immobile,  which  distinguishes  them  from  ordinary  bac- 
teria and  vibrios  and  spirilli.  The  bacteria  of  anthrax 

16* 


186 


A   COURSE   ON    ZOOLOGY. 


multiply  so  rapidly  that  they  often  render  the  blood  of 
animals  infected  with  them  thick  and  muddy.  At  the 
same  time  they  deprive  the  blood  of  oxygen,  and  it 
becomes  black  like  soot,  from  which  the  French  give  to 
the  disease  the  name  charbon  (coal). 

FIG.  114. 


DIFFERENT  KINDS  OF  BACTERIA  (mostly  after  Koch). — A,  micrococci  in  drink- 
ing-water; B,  in  splenic  fever;  C,  in  cholera  (Koch);  D,  from  surface  of 
water :  E,  in  splenic  fever  (in  thread-form,  and  with  incipient  spores) ;  F, 
spirillum,  from  putrefaction ;  G,  spirochsete,  from  the  teeth ;  H,  in  relaps- 
ing fever,  from  blood ;  I,  different  forms  of  cholera  microbe  (Koch). 

It  is  a  special  property  of  microbes  to  develop  and 
multiply  with  great  rapidity.  If  a  few  individuals, 
either  bacteria  or  vibrios,  be  placed  in  a  clear  liquid 
adapted  for  their  development,  in  a  short  time  it  be- 
comes clouded,  and  a  deposit  forms.  This  deposit  is 
composed  entirely  of  microbes,  so  great  is  the  number 


MICROBES.  187 

produced.  It  can  easily  be  understood  that  the  pres- 
ence of  such  a  large  number  of  these  beings  must  modify 
in  some  manner  the  composition  of  the  liquid  in  which 
they  exist,  for  their  development  can  take  place  only  by 
the  removal  from  the  liquid  of  the  elements  required  for 
their  formation.  This  is  the  secret  of  animal  and  vege- 
table decomposition,  of  putrefactions,  and  of  fermenta- 
tions. 

In  the  acetic  fermentation,  which  is  the  conversion 
of  wine,  cider,  or  other  alcoholic  liquid  into  vinegar,  a 
microbe  known  as  the  mycoderma  aceti  does  the  work. 
This  is  formed  of  straight  microbes,  only  six  one-hun- 
dred-thousandths of  an  inch  long,  and  one -third  or  one- 
half  as  thick,  a  number  being  joined  end  to  end,  and  it 
lives  by  transforming  the  alcohol  into  acetic  acid  by  the 
aid  of  the  oxygen  of  the  air.  In  vinegar  factories  the 
mycoderma,  which  forms  a  whitish  membrane  on  the 
surface  of  the  wine  being  soured,  is  carefully  collected 
and  transferred  to  fresh  wine  which  it  is  desired  to  con- 
vert into  vinegar.  It  is  called  mother  of  vinegar. 

We  have  already  said  that  many  contagious  diseases 
are  produced  by  the  presence  of  certain  microbes  in  the 
blood  or  in  other  organs.  It  has  been  found  that  re- 
peated culture  causes  the  microbes  to  lose  their  viru- 
lence,— that  is,  if  the  microbe  which  it  is  wished  to  cul- 
tivate be  introduced  into  a  suitable  liquid,  and  the 
product  of  this  culture  be  collected  and  submitted  to  a 
new  culture,  by  repetition  of  the  process  an  attenuated 
microbe  may  be  obtained  which  occasions  only  slight 
troubles  when  introduced  into  the  system.  Much  more, 
its  presence  or  its  effects  will  prevent  the  development 
of  the  virulent  microbe.  The  attenuated  microbe  may 
constitute  a  vaccine  matter  which  will  protect  the  sys-. 


188  A  COURSE  ON  ZOOLOGY. 

tern  from  the  attacks  of  the  virulent  microbe  of  the 
same  species  as  itself,  but  which  has  not  been  attenuated 
by  culture.  An  excellent  example  of  this  possible  at- 
tenuation of  a  microbe  is  the  vaccine  matter  employed 
as  a  preventive  of  small-pox.  We  know  that  it  is  suffi- 
cient to  take  a  small  quantity  of  the  liquid  contained 
in  the  pustules  on  the  arm  of  a  recently-vaccinated 
child  for  the  purpose  of  fresh  vaccinations.  These  pus- 
tules contain  the  microbes  of  small-pox,  attenuated  by 
culture,  the  culture  substances  being  in  the  organism  of 
the  child.  We  give  this  example  in  order  to  help  to  an 
understanding  of  the  mechanism  of  the  attenuation  of 
microbes,  but  we  must  add  that  while  the  bacteria  of 
anthrax,  of  cholera,  and  of  other  diseases  are  known, 
the  microbe  of  small-pox  has  not  yet  been  isolated  with 
certainty.  In  this  respect  it  is  curious  to  note  that  the 
use  of  the  vaccine  of  variola  as  a  protection  against  small- 
pox was  known  long  before  there  were  the  least  notions 
about  microbes  and  their  attenuation. 


CHAPTER   XXI. 
Principal  Orders  of  Mammals. 

MAMMALS  are  vertebrate  animals,  having  a  constant 
temperature,  a  double  and  complete  circulation,  and  an 
aerial,  pulmonary  respiration.  Their  skin,  though  it 
may  appear  perfectly  naked,  always  has  hairs,  which 
often  cover  it  entirely.  Mammals  produce  living  young, 
which  they  suckle. 

The  head  is  always  articulated  with  the  first  cervical 


MAMMALS.  189 

vertebra  by  a  double  prominence  of  the  occipital  bone. 
The  bones  of  the  trunk  are  in  the  same  relations  to  one 
another  as  in  man,  and  excepting  the  coccygeal  ver- 
tebrae are  about  the  same  in  number.  In  a  small  group 
the  pelvis  has  supplementary  bones,  called  epipubic  or 
marsupial  bones,  which  terminate  in  front  among  the 
muscles  of  the  abdomen.  The  mammals  belonging  to 
this  group  are  also  mostly  characterized  by  the  existence 
of  a  sac,  called  the  marsupial  pouch,  forming  a  fold  in 
the  skin  of  the  belly.  These  mammals,  named  didelphia, 
bring  into  the  world  young  ones  whose  development  is 
very  little  advanced,  and  who  must,  before  they  are  able 
to  walk,  remain  for  a  considerable  time  suspended  at  the 
teats  of  the  mother,  these  teats  being  located  in  the 
marsupial  pouch. 

All  the  other  mammals,  having  no  marsupial  pouch 
and  no  marsupial  bones,  have  been  named  monodelphia. 
Here  is  the  first  basis  for  a  classification.  The  other 
characteristics  are  dependent  on  the  number  of  limbs, 
the  manner  of  life,  the  arrangement  of  the  extremities, 
and  the  modifications  of  the  dental  system. 

These  characters  are  indicated  in  the  table  on  page 
190. 

MAN. 

The  organization  of  man  places  him  at  the  head  of 
the  great  class  mammalia.  Anatomically,  he  is  closely 
related  to  the  monkey,  and  this  has  led  to  his  zoological 
classification  in  the  order  Primates :  the  greatest  ana- 
tomical difference  between  man  and  the  anthropoid  apes 
is  found  in  the  development  of  the  brain.  In  the  first 
chapter  we  have  indicated  the  principal  features  of  man's 
organism. 

The  population  of  the  globe  has  been  classified  by 


190 


A    COURSE   ON    ZOOLOGY. 


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MONOTRI 


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MAN.  191 

naturalists  in  a  certain  number  of  groups  that  are  called 
races.  The  distinctions  between  these  races  are  prin- 
cipally in  the  physical  characters  and  in  the  manners  of 
life  and  languages. 

Among  the  physical  characters,  the  more  important 
are  the  structure  of  the  cranium,  the  form  of  the  face, 
and  the  size  of  the  facial  angle.  The  facial  angle  is 
obtained  by  drawing  two  straight  lines, — one  from  the 
auditory  canal  to  the  base  of  the  nose,  the  other  from 
the  frontal  protuberance  to  the  most  prominent  point  in 
front  of  the  upper  jaw.  This  angle  is  more  and  more 
open  as  the  anterior  part  of  the  forehead  is  more  devel- 
oped and  the  jaws  less  prominent.  Ordinarily  there  is 
a  constant  relation  between  the  development  of  the 
anterior  portion  of  the  skull  and  that  of  the  brain,  and 
a  large  brain  generally  corresponds  to  highly-developed 
intellectual  faculties ;  consequently  a  comparison  of  the 
facial  angle  in  the  different  races  may  throw  some  light 
on  the  relative  intelligence  of  these  races,  and  some  sort 
of  comparison  may  be  made  between  them  and  the 
animals  most  nearly  related  to  man.  There  has  thus 
been  constructed  for  the  human  species  a  sort  of  pro- 
gressive scale,  of  which  the  white  race  occupies  the 
highest  position. 

The  facial  angle  in  the  white  race  has  an  average 
between  eighty  and  eighty-five  degrees ;  in  some  indi- 
viduals it  is  greater  than  a  right  angle.  The  ancients 
understood  the  value  of  the  facial  angle  as  an  indication 
of  intelligence,  and  they  exaggerated  it  in  the  statues  of 
their  divinities.  In  the  Apollo  Belvedere  it  is  nearly 
ninety-five,  and  in  the  Olympian  Jupiter  nearly  one 
hundred  degrees.  In  the  Negro,  the  facial  angle  has  an 
average  of  sixty-five  to  seventy  degrees,  and  in  some  of 


192  A   COURSE   ON    ZOOLOGY. 

the  lowest  African  tribes  it  is  as  low  as  sixty-four, — that 
is,  a  little  lower  than  the  Sai  monkeys,  whose  facial  angle 
is  sixty-five. — and  almost  as  low  as  the  orang-outang, 
which  during  the  earlier  period  of  its  life  has  an  angle 
of  sixty-three,  although  this  afterwards  falls  during 
complete  development  to  thirty-five.  The  angle  of  the 
magot  monkeys  is  not  more  than  forty-five  or  fifty.  In 
the  horse  and  the  pig  it  is  eleven  ;  twenty-five  or  twenty- 
six  in  the  sheep  and  'goat ;  twenty-six  to  thirty  in  the 
dog  ;  thirty  to  thirty-six  in  the  cat. 

The  study  of  the  human  family  has  enabled  its  classi- 
fication into  three  distinct  races  :  the  Caucasian  or  white, 
the  Mongolian  or  yellow,  the  Ethiopian  or  black. 

"The  Caucasian  race  has  received  its  name  because 
traditions  place  its  birthplace  in  the  mountains  of  Cau- 
casus, whence  it  has  spread  by  radiating  migrations  to 
all  parts  of  the  surface  of  the  globe.  One  of  these 
branches  settling  in  Western  Europe  gave  rise  to  the 
Europeans ;  others  travelling  in  different  directions 
spread  over  all  the  regions  of  Western  Asia  and  Northern 
Africa ;  from  these  came  the  Chaldeans,  the  Hebrews, 
Phoenicians,  Arabs,  Persians,  Scythians,  Hindoos,  and, 
probably,  the  Egyptians.  The  Caucasian  race  is  dis- 
tinguished by  the  beauty  of  the  oval  which  outlines  the 
head,  by  the  prominent  forehead,  and  by  the  large  facial 
angle,  which  is  about  eighty  degrees,  as  well  as  by  the 
white  or  only  slightly-tinged  skin. 

"  The  Mongolian  race  appears  to  have  originated  in 
the  Altai  Mountains,  from  which  it  extended  into  Cen- 
tral and  Eastern  Asia  and  the  neighboring  islands. 
The  Tartars,  the  Chinese,  and  the  Japanese  are  the 
principal  branches ;  perhaps,  also,  the  Laps,  the  Green- 
landers,  and  the  Esquimaux  are  descendants  of  the 


MONKEYS. 


193 


same  race,  stunted  by  the  rigors  of  the  climate  in 
which  they  live.  This  race  has  prominent  cheek-bones, 
a  facial  angle  of  about  seventy-five  degrees,  oblique  eyes, 
inclining  downward  at  the  internal  angle,  a  yellow  or 
olive  color,  and  straight  black  hair. 

"  The  Ethiopian  race  inhabits  Africa  south  of  the 
Atlas  Mountains.  It  is  distinguished  by  the  black  or 
very  dark  color  of  the  skin,  a  small  facial  angle, — not 
much  more  than  sixty  degrees, — thick,  projecting  lips, 
flattened  nose,  and  curled,  woolly  hair. 

"  The  natives  of  America  and  Australia  possess  certain 
peculiarities  which  have  rendered  their  classification 
uncertain.  The  cele- 
brated Blumenbach 
made  a  special  race  of 
the  red-man,  but  the 
natural  historians  con- 
sider them  related  to 
the  Caucasians,  while 
the  Australians  are  re- 
garded as  descendants 
of  the  Ethiopian  race." 
(Pouchet.) 

MONKEYS. 

Monkeys  are  of  all 
animals  those  that  most 
closely  resemble  man. 
They  have  been  called 

quadrumana,  from  the         CHIMPANZEE  (after  Hartmann). 
fact     that     in     some 

species  the  four  extremities  are  terminated  by  hands, 
each  provided  with  a  thumb ;  but  in  many  species  only 
n  17 


194  A   COURSE   ON    ZOOLOGY. 

the  posterior  limbs  have  hands,  and  the  name  qiiadrumana 
is  no  longer  used.  In  general,  these  animals  have  a 
narrow  pelvis,  knees  loosely  articulated,  heels  not  very 
prominent,  and  these  features,  together  with  the  feeble 
muscles  of  their  thighs  and  legs,  prevent  them  from 
easily  standing  erect.  Their  hands  are  better  adapted 

FIG.  116. 


GORILLA  (Troglodytes  gorilla). 

for  climbing  than  for  touch  and  prehension.  Most  of 
them  can  climb  trees  with  wonderful  agility,  using  their 
four  hands  in  the  exercise ;  in  this  some  of  them  are 
aided  by  their  tails,  which  are  said  to  be  prehensile, 
having  the  power  of  encircling  and  grasping  objects. 
Monkeys  live  principally  on  vegetable  food,  such  as  fruit, 


MONKEYS. 


195 


FIG.  117. 


young  sprouts,  roots,  etc.,  to  which  they  sometimes  add 
shell-fish,  insects,  little  reptiles,  and  birds'  eggs. 

Monkeys  are  classified  in  three  groups:  the  anthro- 
poid apes,  tailless,  semierect,  and  long-armed ;  the  catar- 
rhini,  dog-nosed  monkeys  of  the  Eastern  Continent ;  and 
the  platyrrhini,  flat-nosed  monkeys  of  South  and  Cen- 
tral America. 

Monkeys  live  principally  in  the  torrid  zone ;  those  of 
the  old  continent  and  those  of  the  new  present  great 
differences,  corresponding  to  the  difference  in  habitation. 
The  Eastern  monkeys  all  have  twenty  molar  teeth,  the 
dental  formula  being  pf  m| ;  many  have  no  tails,  and 
none  have  prehensile  tails ;  the  ischial  prominences  are 
naked,  and  have  ischial  callosities,  usually  red  in  color ; 
many  have  pouches  in  the 
cheeks  opening  into  the 
mouth,  and  in  these  they 
can  carry  a  store  of  provi- 
sions. Among  these  mon- 
keys of  the  Old  World  are 
found  the  largest,  and  those 
most  closely  allied  to  man ; 
of  the  anthropoid  apes  the 
more  important  are  the 

chimpanzee,     the    gorilla,        Hand  (a)  and  foot  (6)  of  gorllla. 
and  the  orang-outang  ;  the 

gibbon  and   the  magot  relate  them  to  the  lower  va- 
rieties. 

The  chimpanzee  and  the  gorilla  inhabit  the  immense 
swampy  woods  of  Africa,  and  travellers  have  brought  us 
many  interesting  stories  of  their  habits  and  of  their 
marvellous  strength.  The  orang-outang  and  the  gibbon 
inhabit  the  forests  of  India  and  the  Indian  Archipelago. 


196 


A   COURSE   ON   ZOOLOGY. 


The  magots,  called   also  Barbary  apes,  are   very  com- 
mon in  Northern  Africa,  and  are  the  only  monkeys  found 


FIG.  118. 


CAPUCHIN  MONKEY. 


living  wild  in  Europe,  there  being,  a  small  colony  of  them 
at  Gibraltar. 


MONKEYS.  197 

The  catarrhini,  or  Old- World  monkeys,  have  thirty-two 
teeth  :  pf ,  c|,  pf ,  mf . 

All  the  American  monkeys,  excepting  the  family  of 
small  monkeys  like  the  marmosets,  have  twenty-four 
molars :  p^,  mj.  The  dentition  of  the  small  monkeys 
is  like  that  of  the  catarrhini.  All  the  American  mon- 

FIG.  120. 


MARMOSETS  (Hapale  jacckua). 

keys  have  tails,  and  the  tails  are  usually  prehensile ;  the 
hind  quarters  are  covered  with  hair,  there  being  no 
ischial  callosities  ;  there  is  no  pouch  in  the  cheeks. 
Among  the  principal  species  are  the  sapajous,  the  spider 
monkeys,  the  howlers,  the  capuchins. 

These  monkeys  inhabit  Brazil,  Paraguay,  Guiana,  and 
a  part  of  Mexico,  there  being  no  monkeys  in  the  tem- 
perate zone. 

17* 


198 


A    COURSE   ON    ZOOLOGY. 


The  lemurs  form  the  lowest  group  of  the  Primates : 
they  appear  to  form  a  connecting  link  between  the 
monkeys  and  the  insectivora.  They  are  interesting 


FIG.  121. 


RING-TAILED  LEMUR  (Lemur  catta). 

little  animals ;  many  of  the  species  are  nocturnal  in  their 
habits,  living  almost  entirely  in  trees,  where  they  feed  on 
fruit,  young  sprouts,  birds'  eggs,  and  even  small  birds 
and  insects ;  they  can  be  easily  tamed.  There  are  a 
number  of  species,  most  of  them  being  found  only  in 
Madagascar ;  some  few  are  found  in  Malaya,  and  others 
in  Africa.  All  are  adapted  for  climbing,  and  their  pow- 
erful hind  limbs  enable  them  to  make  extraordinary 
leaps,  one  of  the  species  passing  readily  from  tree  to  tree 
at  a  distance  as  great  as  ten  yards. 


BATS. 


199 


FIG.  122. 


CHAPTER  XXII. 
Cheiroptera — Insectivora. 

Bats  form  an  order  of  mammals  whose  anterior  limbs 
are  organized  for  flying.  There  are  many  species ;  some 
of  the  larger  ones  are  fruit-eaters  ;  these  are  found  prin- 
cipally in  India  and  Africa.  The  bats  of  the  temperate 
zones  are  usually  small,  and 
feed  entirely  on  insects,  es- 
pecially flying  insects,  such 
as  gnats,  moths,  and  mosqui- 
toes, which  hide  during  the 
day  and  appear  hovering  in 
clouds  in  the  early  evening. 
Our  bats  destroy  immense 
numbers  of  these  troublesome 
creatures,  and  so  render  us  a 
service. 

The  long-eared  bat  is  an 
example  of  enormous  ear- 
development  in  these  mam- 
mals, whose  sight,  on  the  other 
hand,  appears  very  deficient. 
By  hearing,  smell,  and  touch, 
the  last  having  for  its  organ 
the  wing  membrane  which 
spreads  over  the  hand,  as  well 

as  the  ears,  face,  and  lips,  these  creatures  receive  im- 
pressions that  nocturnal  animals  could  not  obtain  by  the 
aid  of  eyes. 


MEGADERMA  GIGAS,  sleeping. 


200 


A   COURSE   ON   ZOOLOGY. 
FIG.   123. 


THE  GREATER  HORSESHOE  BAT  (Rhinolophus  ferrum  equinum),  flying. 


FIG.  124. 


of  (C)  Phyllorhina  tridens,  (D)  Chiromeles  torquatus  (female),  (E) 
Trachyops  cirrhosus,  (F)  Chseronycteris  mexicana. 


INSECTIVORA. 


201 


FIG.  125. 


The  insectivora  are  terrestrial  mammals,  the  four  feet 
being  provided  with  nails  ; 
dentition  is  complete,  the 
molars  bristling  with  coni- 
cal points.  They  feed  on 
earthworms,  insects,  snails, 
frogs,  and  even  snakes, 
their  diet  being  wholly  or 
almost  wholly  carnivorous. 
The  shrews,  the  moles,  and 
the  hedgehogs,  of  each  of  DENTITION  OF  INSECTIVORA. 
which  there  are  several 

spQcies,  are  examples.  Some  live  almost  entirely  under- 
ground, some  are  terrestrial,  while  others  are  largely 
aquatic  in  their  habits. 

FIG.  126. 


COMMON  MOLE  (Talpa  europxd). 

The  mole  is  a  small  animal,  whose  life  is  almost  wholly 
subterraneous ;  it  is  very  rarely  seen  on  the  ground,  for 
it  cannot  walk  well,  although  it  travels  rapidly  under 
ground.  It  is  entirely  inoffensive. 

The  body  of  the  mole  is  cylindrical  and  rather  short ; 
its  head,  which  seems  set  directly  on  the  body,  terminates 


202  A    COURSE    ON    ZOOLOGY. 

in  a  snout  something  like  a  pig's,  and  with  this  the 
creature  digs  in  the  ground.  The  mole  has  very  small 
eyes,  but  they  are  sufficient  for  the  requirements  of 
underground  vision,  and  they  are  covered  and  hidden  by 
long  hairs,  which  protect  them  from  contact  with  the 
soil  that  the  animal  throws  around.  The  most  re- 
markable feature  in  the  structure  of  the  mole  is  the  de- 
velopment of  the  fore-limb,  of  which  all  from  the  wrist 
up  is  enclosed  in  the  skin  of  the  body,  so  that  all  that 
appear  are  two  large  paws  lying  alongside  the  head,  the 
palms  outside.  These  paws  are  very  largely  developed  for 
the  size  of  the  animal,  are  naked,  and  each  has  five  short, 
thick  digits,  armed  with  curved  and  solid  nails.  The 

FIG.  127. 


—°r^ 

b 
a,  section  of  the  habitation  of  a  mole ;  b,  plan  of  ditto. 

hind  limbs  are  much  like  those  of  a  rat,  but  shorter  and 
stronger.  With  his  snout  the  mole  digs  into  and  hollows 
out  the  soil,  and  with  his  paws  he  throws  behind  him  the 
loosened  earth :  he  can  travel  quite  rapidly  in  this  man- 
ner, producing  clean  and  sharply-cut  cylindrical  galleries, 
from  which  from  time  to  time  he  removes  the  rubbish. 

The  mole  feeds  entirely  on  worms  and  the  larvae  of 
insects,  and  in  seeking  such  food  it  digs  its  gallery. 
Sometimes  it  may  injure,  by  exposing  them,  roots  which 
it  encounters  in  its  passage,  but  it  does  not  eat  these 
roots ;  it  would  die  of  hunger  alongside  the  most  juicy 


INSECTIVORA. 


203 


roots  and  herbs.  Far  from  injuring  agriculture,  the  mole 
aids  the  farmer  exceedingly  by  destroying  large  quan- 
tities of  injurious  insects.  It  occasions  inconvenience 
only  by  the  mounds  and  ridges  which  it  sometimes  raises 
in  smooth  lawns. 

The  hedgehog  lives  principally  on  insects,  slugs,  and 
small  reptiles,  but  occasionally  it  takes  vegetable  food. 
Its  habits  are  nocturnal,  and  it  hides  during  the  day.    In 
the  winter  it  disappears, 
sleeping    in    some    hole.  FIG.  128 

The  hair  of  the  hedgehog 
is,  on  the  back,  modified 
into  hard  and  very  sharp 
spines,  forming  for  the 
creature  a  defensive  ar- 


mor   in   which    he    can 

live    in    security.       By 

placing  his  head  and  his 

limbs   against   his   belly 

and    rolling    himself   up,    COMMON  HEDGEHOG  (Erinaceus  europxus). 

he  forms  a  sort  of  prickly 

ball,  in  which  form  he  fears  neither  weasels  nor  birds  of 

prey.     The  fox,  however,  it  is  said,  can  destroy  him. 

The  shrew  seems  to  fill  a  place  between  the  mole  and 
the  mouse.  It  is  smaller  than  the  latter,  and  resembles 
the  mole  in  the  form  of  the  snout,  the  eyes,  ears,  teeth, 
and  limbs.  In  winter  it  lives  in  barns  and  stables,  but 
in  summer  it  lives  in  the  fields,  hidden  under  leaves  and 
moss,  and  showing  itself  seldom  except  at  night.  It 
eats  large  quantities  of  insects,  but  sometimes  feeds  on 
grain.  In  winter  it  travels  long  distances  in  search  of 
food,  and  burrows  deep  into  snow  seeking  stumps  in 
which  it  may  expect  to  find  larvae. 


204 


A   COURSE   ON   ZOOLOGY. 


CHAPTER  XXIII. 
Carnivora. 

BEARS,  DOGS,  CATS,  SEALS,  ETC. 

THE  carnivora  are  mammals  whose  food  consists  en- 
tirely or  principally  of  flesh,  and  whose  organization 
consequently  conforms  with  the  necessities  of  such  a 
diet.  However,  these  animals  possess  certain  peculiari- 
ties of  structure  ;  not  all  flesh-eaters  are  carnivora,  and 

FIG.  129. 


SKULL  OF  TIGER. 

some  carnivora  prefer  a  very  mixed  diet.  Each  jaw  is 
armed  with  six  pointed  incisors,  two  strong,  sharp,  and 
curved  canines,  adapted  for  seizing  and  penetrating 
flesh,  and  molars  capable  of  cutting  it  up.  Sometimes, 
however,  the  molars  are  tubercled,  and  this  is  an  evi- 
dence that  meat  is  not  indispensable  in  the  creature's 
diet.  The  toes  usually  terminate  in  sharp  claws. 


CARNIVORA. 


205 


Carnivora  are  classified  in  two  suborders, — fissipedia, 
having  the. toes  separate,  and  pinnipedia,  having  toes 
united  like  fins.  These  suborders  are  distinguished  and 
divided  into  families  as  follows : 


GROUP. 


FAMILY.     EXAMPLE. 


f  Terrestrial,        or 

only    partially 

• 

Mustelidx  . 

Otter. 

aquatic  ;      cut- 

ARCTOIDEA .... 

Procyonidx 

Raccoon. 

ting   molar  in 

Ailuridse  . 

Panda. 

each  jaw;  inci- 

[ Ursidse  .  . 

Bear. 

Fissi- 

sors  usually  §  .   j 

CYNOIDEA  or 

Canidte.  .  . 

Wolf. 

pedia 

Strong,       sharp,  ' 

curved    claws. 

First  and  fifth 
toes    of    hind 

Felidse  .  . 
AILUROIDEA.  .  .  J  Viverridx. 

Cat. 
Civet. 

foot  not  longer 

[Hyxnidx  . 

Hyena. 

than  others. 

Aquatic,    except  ' 

Small      external  ' 

at  birth.    Very 
uniform      mo- 

ears.         Hind 
limbs       flexed 

Otariidx  . 

Fur  seals. 

lars.      Incisors 

forward. 

fewer  than    |. 

Enormous       ca- 

Pinni- 
pedia 

Webbed     feet  ; 
outer  and  inner 

nines  in  upper 
jaw. 

Trichechidx. 

Walrus. 

toe  of  hind  foot 

No     outer     ear.  " 

\ 

longer         and 
stronger     than 

Hind         limbs  J 
flex  backward  \Phocid3e-  i 

Hair  seals. 

others. 

only. 

) 

ARCTOIDEA. 

The  word  arctoidea  signifies  bear-like,  and  the  group 
includes  the  bears  and  many  species  which  at  first  would 
not  seem  related  to  the  bears,  but  they  are  all  similar  in 
the  structure  of  the  skull,  in  the  absence  of  the  caecum 
from  the  digestive  apparatus,  and  in  certain  other  pecu- 
liarities. 

The  otters  have  palmate  feet  and  a  tail  flattened  hori- 
zontally. They  are  organized  for  passing  a  large  portion 

18 


206  A  COURSE  ON  ZOOLOGY. 

of  time  under  water,  being  able  to  walk  only  with  diffi- 
culty, but  to  swim  very  rapidly.  They  inhabit  the 
banks  of  streams  and  ponds,  living  in  holes  close  to  the 
water's  edge.  They  live  principally  on  fish,  of  which 
they  destroy  enormous  quantities.  The  fur  is  a  beau- 
tiful chestnut  color  above,  whitish-gray  below,  and  is 
much  prized.  The  otter  attains  a  length  of  three  or 

four  feet. 

FIG.  130. 


SEA-OTTER  (Enhydra  lutris). 

Other  members  of  the  family  mustelidse  are  the  pole- 
cat, the  pekan,  or  American  marten,  the  ermine,  ferret, 
sable,  skunk,  badger,  and  other  martens,  and  weasels. 

The  polecats,  of  which  the  ferret  is  one  variety,  are 
characterized  by  a  very  unpleasant  odor,  which  they 
seem  to  be  able  to  control  to  some  extent.  They  prefer 
to  live  near  farm-houses,  sometimes  making  their  homes 
in  barns  and  stables ;  they  are  bold  and  ferocious,  and 
often  kill  wantonly  large  numbers  of  barn-yard  fowl, 
carrying  off  only  a  small  fraction  of  their  prey.  The 
fur  is  brown  on  the  back,  fawn-colored  on  the  sides, 
yellowish  on  the  belly,  and  white  on  the  nose ;  it  is  a 


MUSTELINE.  207 

soft,  warm  fur,  but  always  retains  a  somewhat  unpleas- 
ant odor.  The  polecat  attains  fifteen  or  sixteen  inches 
in  length,  without  including  the  tail.  The  name  polecat 


FIG.  131. 


POLECAT  (Musteta  putorius). 

is  sometimes  applied  to  the  skunk,  which  is  an  entirely 
different  animal.  The  ferret,  which  is  often  employed 
in  hunting  rabbits  and  rats,  is  a  sort  of  tamed  polecat. 

The  wolverene  or  glutton  of  Canada  is  the  largest  of 
the  mustelidse,  and  next  comes  the  pekan  or  wood-shock, 

FIG.  132. 


THE  GLUTTON  (Gulo  luscus.) 


a  sort  of  marten,  whose  length  from  the  tip  of  his  nose 
to  the  end  of  his  tail  may  be  four  and  a  half  feet.  The 
pekan  is  often  called  fisher  and  black-fox. 

The  weasels  and  martens  are  brown,  but  the  neck  of 


208  A   COURSE   ON  ZOOLOGY. 

the  former  is  white.  Weasels  are  very  destructive  to 
poultry.  The  sable  is  found  in  Siberia,  and  is  cele- 
brated for  the  beauty  of  its  fur,  which  is  a  dark  chest- 
nut, exceedingly  fine,  and  lying  smoothly  in  either 
direction.  The  skunk  is  an  American  animal,  about  as 
large  as  a  common  cat ;  its  fur  is  almost  black,  more  or 
less  mixed  with  white.  It  is  sold  as  Alaska  sable.  The 
skunk  has  a  peculiar  means  of  defence  and  offence :  it 
has  in  the  groin  a  pair  of  sacs  with  muscular  walls,  and 
these  sacs  secrete  a  fluid  of  most  disgusting  odor,  that 
the  animal  can  project  upon  its  enemies  or  annoyers, 
putting  them  to  instant  flight. 

FIG.  133. 


SKUNK. 

The  badgers  walk  on  the  whole  sole  of  the  foot,  and 
not  on  the  forepart  of  it,  thus  differing  from  the  pre- 
ceding species  ;  they  were,  therefore,  once  classified  with 
the  bears  as  plantigrade  carnivora,  while  the  other  fam- 
ilies were  called  digitigrade ;  but  this  classification 
brought  together  so  many  unrelated  species,  and  sepa- 
rated so  many  others  which  are  evidently  very  similar, 
that  it  has  been  abandoned,  though  we  may  use  the 


BADGER — RACCOON. 


209 


terms  as  descriptive.     The  head  of  the  badger  is  long, 
its  muzzle  pointed ;  there  are  five  toes  on  each  foot,  and 


FIG.  134. 


BADGER  (Meles  vulgaris). 


the  feet  are  adapted  for  burrowing.     The  average  length 
is  two  feet  and  a  half.    The  hair  is  coarse,  grayish-brown, 


FIG.  135. 


RACCOON  (Procyon  lotor). 

and   touches  the   ground  as  the  animal   walks.      The 
badger  is  not  entirely  carnivorous ;  its  food  consists  of 
o  18* 


210 


A  COURSE   ON   ZOOLOGY. 


fruits,  nuts,  roots,  and  eggs,  as  well  as  small  quadrupeds, 
birds,  frogs,  etc. 

The  raccoon  is  a  curious  little  animal  of  the  family 
procyonidae.  It  grows  to  a  length  of  about  two  feet ; 
its  muzzle  is  very  pointed,  its  body  short  and  thick,  its 
fur  is  brownish,  its  tail  bushy  and  ringed.  Its  legs  are 
rather  short.  It  is  omnivorous.  It  uses  its  forefeet 
with  great  readiness  for  prehension. 

The  panda  is  a  rare  animal,  whose  position  is  inter- 
Em.  136. 


COMMON  BROWN  BEAR  ( Ursus  arctos). 

mediate  between  the  raccoons  and  the  bears.  It  lives 
at  high  altitudes  in  the  Himalayas  and  in  Thibet ;  it  is 
about  as  large  as  a  large  cat ;  it  has  reddish-brown  fur 
and  a  bushy  tail  almost  as  long  as  the  body,  and  ringed 
with  red  and  yellow. 


BEARS.  211 

Bears  are  found  in  Europe,  Asia,  America,  and  in  the 
higher  and  cooler  parts  of  hot  countries.  They  all  have 
bodies  comparatively  short  for  the  thickness,  and  inhabit 
the  most  savage  parts  of  mountains  and  forests,  where 
they  lead  a  solitary  life.  They  have  strong,  curved  claws, 
which  serve  them  especially  in  digging  and  climbing,  and 
are  more  rarely  used  in  attack.  Most  of  them  prefer 
vegetable  to  animal  food,  living  on  fruits,  nuts,  roots, 

FIG.  137. 


POLAR  BEAR  (Ursus  maritimus). 

and  tender  sprouts  ;  they  are  particularly  fond  of  honey. 
During  the  winter  they  retire  to  caves  or  sheltered 
spots,  and  sleep  until  spring-time  :  they  are  said  to  hiber- 
nate. 

Among  the  better-known  bears  are  the  brown  bear  of 
Europe,  the  black  bear  of  North  America,  the  polar  bear 
of  the  far  North,  the  grizzly  bear  of  the  Eocky  Mountains, 
and  the  cinnamon  bear  of  the  same  locality.  The  brown 
and  black  bears  are  not  usually  disposed  to  attack  man, 


212 


A  COURSE  ON  ZOOLOGY. 


but  the  other  three  species  named  are  more  carnivorous 
in  diet,  and  the  grizzly  and  polar  bears  are  dangerous 
adversaries  in  combat.  The  black  and  brown  bears,  when 
fully  grown,  are  about  six  feet  long,  and  have  at  the 
shoulder  a  height  of  about  three  feet.  The  grizzly  is 
larger,  and  the  polar  bear  is  often  nine  feet  long. 

CYNOIDEA. 
This  group  includes  wolves,  foxes,  jackals,  and  dogs. 

FIG.  138. 


WOLF. 

The  European  wolf  is  very  like  the  gray  wolf  of  North 
America.  Its  color  is  a  slightly  yellowish  gray,  with 
some  black  hairs  intermingled.  It  is  about  the  size  of  a 
large  dog,  its  height  at  the  shoulder  being  between  two 
and  two  and  a  half  feet.  In  the  farming  countries  of 
Europe  it  frequently  does  great  damage  to  the  flocks, 
and  when  pressed  by  hunger  will  attack  man ;  but  it  is 


WOLVES   AND   POXES. 


213 


naturally  of  a  cowardly  disposition.  Some  individuals 
are  black.  It  prefers  to  live  in  forests.  The  coyote  or 
prairie-wolf  is  much  smaller,  but  similar  in  appearance. 


FIG.  139. 


COYOTE. 


The  fox  has  relatively  a  much  larger  head  than  the 
dog ;  its  ears  are  shorter,  its  tail  longer,  its  hair  longer 


FIG.  140. 


COMMON  FOX  (Vulpes  alopex). 


and  thicker,  its  eyes  more  oblique.     Its  characteristics 
are  much  influenced  by  climate,  and  there  are  almost  as 


214  A   COURSE   ON   ZOOLOGY. 

many  varieties  of  foxes  as  there  are  of  any  species  of 
domestic  animals.  Most  foxes  are  red,  but  many  have 
grayish  fur ;  in  northern  countries  there  are  all  colors 
and  shades, — black,  iron-gray,  silver-gray,  and  white. 
The  blue-  fox  inhabits  the  north  of  both  continents ;  its 
ash-gray  fur  is  exceedingly  valuable,  as  are  also  those  of 
the  silver  and  black  foxes. 

Jackals,  sometimes  called  golden  wolves,  are  found  in 
Africa,  Central  Asia,  Turkey,  and  Greece.  They  are 
troublesome  destroyers  of  fowls  in  the  country,  and  in 
the  neighborhood  of  cities  collect  in  large  bands,  and 
prowl  around  at  night  hunting  animal  refuse.  They  are 
smaller  than  wolves,  and  their  fur  is  fawn-color. 

FIG.  141. 


COMMON  JACKAL  (Canis  aureus). 


The  dog  is  classed  with  the  foxes  and  wolves,  and  we 
need  add  nothing  to  what  has  been  said  in  Chapter  VIII. 


AILUROIDEA. 


This  group  includes  the  cat-like  animals,  as  the  name, 
of  Greek  origin,  indicates, 


LION — TIGER — LEOPARD. 


215 


.  The  lion  is  distinguished  from  all  the  other  species  by 
its  almost  uniform  fawn  color,  by  the  tuft  of  hairs  on  the 
end  of  its  tail,  and  by  the  heavy  mane  that  covers  the 
head  and  shoulders  of  the  males.  It  anciently  existed 
over  nearly  all  the  Old  World,  but  is  now  found  only  in 
Africa  and  less  abundantly  in  Asia.  It  sometimes  at- 
tains a  length  of  eight  or  nine  feet,  and  stands  as  high 
as  four  and  a  half  feet  at  the  shoulder. 
FIG.  142. 


LION  (Felis  leo). 

The  tiger  lives  in  India,  and  is  recognized  by  its  fur, 
which  is  fawn-colored  above,  white  beneath,  and  striped 
vertically  with  black  lines.  It  is  more  slender  and  some- 
what smaller  than  the  lion.  The  panther  inhabits  Asia 
and  Africa ;  it  is  spotted  with  rows  of  black  spots,  joined 
together  in  rosettes.  It  is  probably  identical  with  the 
leopard,  which  is  found  in  the  same  countries.  One 
variety  is  black.  The  jaguar,  or  American  leopard,  has 
eye-like  spots,  more  regularly  arranged  than  those  of  the 
leopard.  It  is  found  all  over  South  America,  and  in 


216 


A  COURSE  ON  ZOOLOGY. 


North  America  as  far  north  as  Texas  and  South  Carolina; 
The  puma  of  the  Northern  United  States  and  Canada  is 


FIG.  143. 


CHARACTERISTIC  FEATURES  OF  THE  FELIDJE.— a,  tiger's  head;  6,  portion  of 
tongue ;  c,  right  fore-paw,  showing  claws ;  d,  claw,  showing  tendons. 

FIG.  144. 


JAGUAR  (Felis  onca). 


almost  as  large  as  the  tiger.     Its  color  is  a  uniform  gray, 
somewhat  lighter  below,  and  the  borders  of  its  mouth 


LYNXES. 


217 


are  white.     The   lynxes  of  Europe  and   America  are 
smaller  animals  than  those  we  have  named,  and  more 


FIG.  145. 


THE  EUROPEAN  LYNX  (Lynx  virgatus). 
FIG.  146. 


nearly  like  the  domestic  cat.     The  color  is  grayish,  with 
a  tendency  to  black  on  the  back. 


19 


218  A   COURSE   ON   ZOOLOGY. 

All  these  animals  are  distinguished  from  other  carniv- 
ora  by  the  arrangement  of  the  claws,  which  are  retrac- 
tile,— that  is,  capable  of  being  thrown  out  and  withdrawn. 
These  curved  and  hooked  claws  constitute  formidable 
weapons. 

The  domestic  cats  are  probably  descended  from  the 
wild-cat  found  in  the  forests  of  Europe.  The  wild-cat  is 
yellowish  gray  with  dark  stripes,  which  are  longitudinal 
on  the  back  and  transverse  on  the  flanks.  The  domestic 
cat  presents  extreme  variations  in  color,  and  this  lack 
of  uniformity  in  color  is  general  in  all  animals  that  have 
become  domesticated ;  only  in  the  savage  state  does  an 
animal  possess  a  fixed  and  characteristic  color. 

FIG.  147. 


SPOTTED  HYENA  (Hysena  crocuta). 

The  civet  represents  a  family  of  digitigrade  carnivora 
having  long,  thin  bodies,  pointed  heads,  and  short  legs. 
The  larger  species  are  as  large  as  foxes.  The  strong 
perfume  called  civet  is  obtained  from  glands  situated 
near  the  anus  of  these  animals.  The  ichneumon  is 


SEALS.  219 

another  representative  of  the  same  family,  called  viver- 
ridae. 

The  hyenas  live  in  warm  climates  of  the  Old  World  ; 
at  night  they  infest  cemeteries,  disinterring  the  ca- 
davers;  but  they  are  afraid  of  man,  and  attack  him 
only  when  excited  by  the  last  pangs  of  hunger.  A 
characteristic  which  enables  one  to  recognize  the  hyenas 
when  once  seen  is  their  curious  oblique  walk  and  the 
strange  appearance  presented  by  the  hind  quarters, 
which  are  always  lower  than  the  foreparts. 

PINNIPEDIA. 

The  pinnipedia  resemble  the  terrestrial  carnivora  in 
their  complete  dentition,  their  cutting  molars,  and  their 

FIG.  148. 


COMMON  SEAL  (Phocidx  vitulina) ;  attitude  when  swimming. 

carnivorous  diet ;  but  they  are  distinguished  by  the  form 
of  the  limbs,  which  are  short,  arranged  like  fins,  and 
not  adapted  for  terrestrial  locomotion,  and  by  their  gen- 
eral form,  which  is  elongated  like  that  of  a  fish ;  the 
head  resembles  that  of  a  dog. 
The  otariidae,  or  fur-seals,  differ  from  the  other  seals  in 


220  A   COURSE   ON   ZOOLOGY. 

possessing  an  external  ear.  Certain  peculiarities  of  form 
have  gained  for  the  diiferent  species  the  names  sea-lion, 
sea-bear,  sea-elephant,  etc.  The  sea-bear  of  the  North 
Pacific  furnishes  the  fur  from  which  seal-skin  garments 
are  made. 

The  phocidae,  or  common  hair-seals,  are  found  in  all 
cold  seas,  and  a  few  species  even  occur  in  the  tropics. 
The  sea-calf,  so  called  on  account  of  its  peculiar  cry,  is 
the  most  common  in  temperate  waters. 

Seals  are  very  intelligent,  are  easily  tamed,  and  thrive 
well  in  captivity.  They  feed  on  fish  and  crabs,  and  live 

FIG.  149. 


WALRUS. 

in  herds  near  the  coasts,  where  they  may  be  sometimes 
seen  playing  on  the  waves,  sometimes  resting  on  the 
sand-banks.  The  thick  layer  of  fat  that  surrounds  their 
bodies  enables  them  to  move  through  the  water  without 
exerting  any  apparent  effort  to  keep  afloat. 

The  trichecida  or  walrus,  which  is  sometimes  called 
sea-cow  and  sea-horse,  has  two  enormous  canines  in  the 


RODENTIA. 


221 


upper  jaw,  and  these  he  uses  as  a  means  of  defence  and 
to  assist  in  climbing  on  the  ice.  The  walrus  attains  a 
length  of  ten  or  twelve  feet ;  the  seals  are  smaller,  ex- 
cepting the  sea-elephant,  which  is  said  to  grow  as  long 
as  thirty  feet. 


CHAPTER  XXIV. 
Rodentia — Edentata. 


RODENTIA. 

THE  rodents  are  mostly  terrestrial  mammals,  having 
four  clawed  feet  and  incomplete  dentition.  They  have 
no  canines ;  the  incisors  have  chisel-like  edges,  and  are 
curved  in  a  circular  arc,  the  convexity  outward  ;  besides 
they  grow  indefinitely  during  life,  so  that  they  are 
pushed  out  at  the  base 
as  they  are  worn  away  FIG-  150. 

at  the  edge,  and  the 
posterior  surface  wears 
more  rapidly  than  the 
anterior,  whose  enamel 
is  harder.  This  struc- 
ture indicates  the  diet 
of  the  animals,  organ- 
ized for  gnawing  every- 
where and  continually, 
and  in  whom  the 
gnawing  instinct  pre- 
dominates nearly  all  others, 
the  incisors  and  the  molars. 

19* 


SKULL  OF  COMMON  PORCUPINE  (Hystrix  cris- 
tata).— The  lower  jaw  partly  in  section  to 
show  the  lower  incisor  tooth. 


There  is  a  space  between 


222 


A   COURSE   ON    ZOOLOGY. 


Rodents  have  the  upper  lip  slit  vertically,  giving  a  pe- 
culiar physiognomy;  this  condition  occurs  sometimes  in 
man  as  a  defect,  and  is  called  harelip.  Generally,  rodents 
are  herbivorous  or  frugivorous ;  some,  however,  such  as 
rats,  are  omnivorous.  Most  of  them  are  small ;  the 
limbs  are  organized  for  jumping  rather  than  walking, 
the  hind  quarters  being  higher  than  the  shoulder.  The 
brain  is  not  highly  developed.  They  are  timid,  and  only 
moderately  intelligent,  although  endowed  with  remark- 
able instincts.  Nearly  all  are  nocturnal,  digging  gal- 
leries, and  passing  three-fourths  of  their  existence  under- 
ground ;  some  are  semi-aquatic,  and  a  few  live  in  trees. 
In  general  they  have  an  instinct  of  foresight,  and  lay 
up  for  winter  a  store  of  provisions,  consisting  of  grains 
and  fruits,  in  quantity  much  greater  than  their  real  ne- 
cessities require.  Sev- 
eral hibernate  during 
the  cold  season. 

Of  all  the  orders  of 
mammals  the  rodents 
are  most  widely  dis- 
tributed over  the 
earth's  surface,  repre- 
sentatives being  found 
in  every  country  on 
the  globe.  There  are 
more  than  six  hundred 
species ;  many  of  them 
may  be  considered  use- 

COMMON  SQUIRREL  (Sciurus  vuigaris).       ful  to  us,  because  we 

use  their  skins  for  furs 

and  their  flesh  for  food ;  but  the  necessities  of  their  diet 
nearly  always  render  them  injurious  to  agriculture,  es- 


FIG.  151. 


SQUIRRELS. 


223 


pecially  on  account  of  their  instinct  for  storing  food. 
The  most  interesting  species  are  the  squirrels,  marmots, 
beavers,  dormice,  rats,  mice,  voles,  lemmings,  chinchillas, 
muskrats,  capybaras,  porcupines,  agoutis,  guinea-pigs, 
hares,  and  rabbits.  All,  except  the  hare  and  rabbit,  have 
only  one  pair  of  upper  incisors,  the  enamel  being  only  in 
front.  Hares  and  rabbits  have  four  upper  incisors,  the 
enamel  extending  around  the  teeth. 

Squirrels  are  found  in  the  forests  of  both  continents. 


FIG.  152. 


CHIPMUNK  (Tamias  striatus). 

They  live  on  grains,  fruits,  and  nuts,  and  make  their 
homes  in  hollow  trees.  The  common  squirrel  is  bright 
red,  with  a  white  belly.  The  gray  squirrel  has  a  soft 
light  fur,  which  is  the  object  of  considerable  commerce. 
In  this  variety  the  back  is  a  beautiful  bluish  gray,  the 
hair  being  dark  gray  at  the  roots  and  silver-gray  at  the 
tips  ;  the  belly  is  pure  white. 

The  chipmunk  is  a  small   species  of  squirrel,  often 


224 


A  COURSE  ON  ZOOLOGY. 


called  the  ground-squirrel,  common  in  North  America. 
It  lives  in  underground  burrows. 

Marmots  are  found  all  over  Europe,  Asia,  and  North 
America ;  they  abound  in  the  Alps.  They  pass  the  greater 
part  of  their  existence  in  burrows,  in  which,  on  the  ap- 
proach of  winter,  they  enter  that  lethargic  sleep  that  char- 
acterizes hibernating  animals.  The  woodchuck  is  our 
largest  marmot,  its  length  being  about  fourteen  inches. 

FIG.  153. 


THE  ALPINE  MARMOT  (Arctomys  marmotta). 

The  prairie-dogs  of  the  western  United  States  are 
closely  allied  to  the  marmots.  They  construct  what  are 
called  prairie-dog  villages,  and  it  is  said  that  their  habi- 
tations are  shared  with  the  rattlesnake  and  the  owl. 
They  are  rather  larger  than  rats. 

The  beaver  is  one  of  the  largest  rodents,  attaining  a 
length  of  two  and  a  half  feet.  It  has  a  flat,  scaly  tail, 
and  the  hind  feet  are  webbed,  all  the  toes  having  claws. 
It  is  a  semi-aquatic  animal,  celebrated  for  the  ingenious 
manner  in  which  it  constructs  lodges  and  dams  with 


RATS.  225 

branches  of  trees  and  mud,  but  aside  from  this  instinct 
showing  little  intelligence.  It  is  found  occasionally  in 
France  and  Germany,  and  was  formerly  very  abundant 
in  North  America,  where  it  lived  in  large  colonies,  and 
constructed  lodges  that  excited  the  admiration  of  travel- 
lers. Under  the  hair  of  the  beaver,  which  is  usually  of 

FIG.  154. 


PRAIRIE-DOGS  (Cynomys  ludovidanus). 

a  reddish  color,  is  a  fine  gray  down  that  makes  the  fur 
much  esteemed. 

The  rats  include  a  number  of  species,  much  alike  in 
appearance  and  in  habits.  Properly,  the  rats  may  be  clas- 
sified as  black  rats  and  brown  rats.  The  black  rats  in- 
vaded Europe  at  the  time  of  the  Crusades,  and  during 
several  centuries  ravaged  the  country  and  the  cities. 
About  a  hundred  years  ago  a  few  individuals  of  the 
brown  species  were  brought  from  Persia ;  they  multi- 
plied rapidly,  and  waged  such  a  terrible  war  on  the 
black  rats  that  the  latter  were  driven  from  the  cities. 

The  field-rat  is  smaller  than  the  house-rat  and  larger 
P 


226 


A   COURSE   ON   ZOOLOGY. 


than  a  mouse.  It  lives  in  the  fields,  where  in  its  burrows 
it  lays  up  prodigious  stores  of  nuts  and  grain ;  a  single 
individual  will  sometimes  collect  more  than  a  bushel. 


FIG.  155 


BEAVERS  AND  BEAVER-LODGE. 

The  dwarf  field-rat  makes  its  home  in  the  stubble-fields, 
and  cuts  off  the  stalks  in  order  to  obtain  the  spikes. 

Mice  originated  in  Europe,  whence  they  have  been 
distributed  by  ships  to  all  parts  of  the  world.  They 
prefer  the  interior  of  dwellings,  in  which  their  omniv- 
orous appetite  and  their  odor  render  them  a  nuisance. 

The  dormouse  is  analogous  to  both  the  rat  and  the 
squirrel.  It  lives  on  trees,  and  often  does  much  injury 
in  orchards  by  its  propensity  for  fruit-eating. 

The  following  species  have  short  tails,  and  are  called 
voles :  The  field-  or  meadow-mice,  a  number  of  species, 
all  more  or  less  destructive  to  agriculture.  The  common 


RODENTIA. 


227 


field-mouse  is  especially  abundant  in  Europe,  where  it 
sometimes  multiplies  so  rapidly  that  it  destroys  whole 
crops.  It  is  as  large  as  a  common  mouse,  brownish 
yellow  on  the  back,  and  dirty  white  below.  The  water- 
rat  is  about  as  large  as  the  ordinary  black  rat ;  it  lives 
on  the  banks  of  streams  and  ponds,  and  feeds  on  roots, 
aquatic  plants,  frogs,  insects,  and  little  fish. 

FIG.  166. 


MUSQUASH  (Fiber  zibethicwi). 

The  lemmings  have  still  shorter  ears  and  tail  than  the 
voles  ;  the  body  is  heavier  and  the  claws  stronger.  They 
are  about  the  size  of  the  ordinary  rat,  and  are  found  in 
Siberia  and  Northern  North  America.  In  Northern 
Scandinavia  they  multiply  so  rapidly  that  they  periodi- 
cally migrate  in  large  numbers,  swimming  rivers,  cross- 
ing mountains,  devouring  whatever  they  come  across, 
and  breeding  and  dying  on  the  way. 


228  A  COURSE  ON  ZOOLOGY. 

The  musk-rat,  or  more  properly  musquash,  is  a  large 
rodent,  its  head  and  body  measuring  about  fifteen  inches, 
and  its  tail  ten  inches.  It  is  very  aquatic,  rarely  being 
found  far  away  from  the  banks  of  the  stream  or  pond 
near  which  it  lives.  It  burrows  under  the  banks,  the 
entrance  to  its  hole  being  under  water.  Its  food  is 
principally  vegetable.  Its  dark-brown,  downy  fur  is 
rather  short,  but  mixed  with  longer  and  stiifer  hairs, 
and  is  in  considerable  demand. 

The  chinchilla  is  best  known  by  its  soft  gray  fur.  It 
inhabits  high  altitudes  in  Chili  and  Peru.  Its  body  is 
about  a  foot  long,  and  it  somewhat  resembles  a  squirrel, 
but  its  hind  legs  are  longer. 

FIG.  157. 


CAPYBAKA  (Hydrochwrus  capybara). 

The  capybara  is  the  largest  rodent,  being  as  large  as 
a  small  pig,  and  much  resembling  in  form  the  guinea- 
pig.  It  is  aquatic  in  its  habits  and  vegetarian  in  diet. 
It  has  thin,  coarse,  and  brownish  hair.  It  is  found  in 
Northern  South  America,  where  it  is  known  as  the 
water-hog. 


PORCUPINES. 


229 


The  porcupine  is  quite  common  in  the  south  of  Europe. 
Like  the  hedgehog,  it  has  a  natural  defensive  armor, 


FIG.  158. 


FIG.  159. 


COMMON  PORCUPINE  (Hystrix  criatata). 

formed  of  sharp,  stiff  spines,  which  bristle  out  from  the 

body,  and  which  may  grow  to  a  length  of  a  foot  and  a 

half.      These  spines 

are      alternately 

banded    white    and 

black.       Porcupines 

are     nocturnal      in 

their    habits ;    they 

live  in  burrows  and 

hibernate  in  winter. 

A  species  of  porcu- 


AGOUTI  (Dasyprocta  agouti). 


pine,    the   urson,    is 
found   in    the    Nor- 
thern United  States  and  Canada,  where  it  is  generally 
but  erroneously  called  hedgehog. 

The  agouti  is  a  small  South  American  rodent,  having 
20 


230 


A    COURSE    ON    ZOOLOGY. 


coarse  brown  or  yellow  hair.     It  has  slender  legs,  with 
three  toes  on  the  hind  feet. 

Guinea-pigs  came  originally  from  Brazil,  but  they  are 
now  domesticated  in  nearly  all  countries. 

FIG.  160. 


GUINEA-PIG. 


The  hares  have  very  long  ears ;  their  fore  legs  arc 
much  shorter  than  the  hind  ones ;  they  can  consequently 

FIG.  161. 


COMMON  HARE  (Lepus  timidus). 


move  only  by  a  series  of  jumps,  a  sort  of  gallop.  The 
agility  of  their  movement  is  the  only  resource  they  have 
when  they  are  pursued  by  enemies.  Their  fur  has  some 
commercial  value,  and  their  flesh  is  much  esteemed. 


EDENTATA.  231 

Hares  are  solitary  in  habit,  but  make  their  abodes  not 
far  from  one  another.  They  live  on  herbs,  roots,  leaves, 
fruit,  and  grain,  and  even  gnaw  the  bark  off  trees. 
They  sleep  during  the  day,  and  are  active  only  at  night. 
Rabbits  are  smaller  than  hares,  and  have  shorter  ears 
and  tail.  Their  flesh  is  whiter  than  that  of  the  hare. 
They  are  very  fecund,  it  having  been  calculated  that  the 
progeny  of  a  single  pair  would  in  four  years  number 
twelve  hundred  thousand.  In  countries  adapted  to  them 
these  animals,  therefore,  multiply  so  rapidly  that  the 
soil  can  hardly  yield  crops  enough  for  them,  and  they 

become  pests  to  the  farmer ; 

,,-.      .    J  FIG.  162. 

this    is    now    the    case  in 

certain   provinces  of  Aus- 
tralia. 

EDENTATA. 

The  mammals  compos- 
ing this  order  have  for  a 
common  characteristic  the 
absence  of  front  teeth; 
some  have  no  teeth  at  all. 
By  way  of  compensation 
they  have  very  well-de- 
veloped claws.  None  of 
them  occur  in  Europe  or  in 

the  United  States. 

SLOTH. 
As  examples  of  edentata 

we  will  consider  the  sloths,  the  armadillos,  the  pango- 
lins, and  the  ant-eaters. 

The  sloth  is  a  South  American  animal,  about  the  size 
of  a  cat,  and  looks  like  a  deformed  monkey ;  its  limbs 
are  not  adapted  for  walking,  and  it  lives  suspended  from 
the  branches  of  trees. 


232 


A  COURSE  ON  ZOOLOGY. 


The  armadillos   possess  a  scaly  covering  which   en- 
velops the  body  like  a  cuirass,  and  by  which  they  are 


FIG.  163. 


THREE-BANDED  ARMADILLO  (Dasypus  apar). 

almost  as  well  protected  as  are  hedgehogs  and  porcu- 
pines.    They  are  nocturnal,  burrowers,  and  inoffensive. 

FIG.  164 


GREAT  ANT-EATER  (Myrmecophaga  jubata). 

The  pangolins  are,  like  the  armadillos,  enveloped  in  a 
scaly  coat,  but  they  are  absolutely  without  teeth,  and 
are  compelled  to  live  on  ants  that  they  catch  by  the 


UNGULATA. 


233 


hundred  with  their  long,  viscous  tongues.     They  are 
inhabitants  of  the  Orient  and  Ethiopia. 

The  ant-eaters  of  South  America  have  no  teeth ;  the 
muzzle  is  elongated  like  a  proboscis,  and  by  the  aid  of 
the  long,  viscous  tongue,  sometimes  half  a  yard  in 
length,  they  can  lap  up  ants  and  termites  (large  white 
ants),  after  they  have  torn  down  the  ant-hills  with  their 
powerful  claws.  There  are  several  species  of  ant-eater. 


FIG.  165. 


CHAPTER  XXV. 
Ungri  lata — Artiodactyla. 

THOSE  mammals  that  have  the  horny  extremity  of 
the  feet  developed  into  hoofs  are 
called  ungulata.  The  order  in- 
cludes a  great  number  of  species ; 
in  some  the  number  of  toes  is  odd, 
in  others  it  is  even,  and  an  excel- 
lent classification  is  based  on  this 
difference.  Those  having  an  even 
number  of  toes  are  called  artiodac- 
tyla,  and  this  class  includes  the 
ruminants,  the  hippopotami,  and  the 
swine  families.  The  ruminants  are 
distinguished  by  a  complex  stomach, 
and  comprise  the  deer,  oxen,  sheep, 
giraffes,  and  camels.  Those  un- 
gulates having  an  odd  number  of 
toes— and  this  number  does  not  HORSE.  ox. 

exceed  five — are  called  perissodac- 
tyla ;  among  these  are  the  horse,  ass,  zebra,  tapir,  and 
rhinoceros.     The  elephant  has  five  toes,  but  he  is  the 

20* 


234 


A   COURSE   ON   ZOOLOGY. 


only  living  representative  of  a  suborder,  called  probos- 
cidea, 


FIG.  166. 


RHINOCEROS. 


HIPPOPOTAMUS. 


ELEPHANT. 


FIG.  167. 


RUMINANTS. 

The  ruminants  or  cud-chewing  mammals  are  herbiv- 
orous, and  flesh  forms  no  part  of  their  food.  Their 
teeth  are  not  sharp-edged,  but  flat,  and 
adapted  for  grinding;  their  digits  do 
not  terminate  in  claws,  but  in  a  horny 
hoof,  a  means  of  defence  and  not  of 
attack.  In  all  the  ruminants  this  hoof 
is  split  in  the  median  line,  and  so  forms 
a  bifurcated  sheath  for  the  two  toes 
that  compose  the  foot;  ruminants  are 
said  to  be  cloven-footed.  Lastly,  the 
upper  jaw  is  usually  without  incisors, 
and  the  stomach  has  four  distinct  com- 
MOLAR  OP  AN  ox.  partments. 

The  details  of  the  digestive  functions 
of  ruminants  are  very  different  from  those  of  animals 
whose  stomachs  form  a  simple  sac.  When  an  ox  eats, 
he  simply  swallows  the  grass,  almost  without  mastica- 


RUMINANTS. 


235 


FIG.  168. 


tion,  and  this  is  stored  in  the  first  stomach,  which 
is  called  the  paunch,  or  rumen,  and  the  second,  or 
reticulum,  which  is  lined  with  hexagonal  cells.  These 
first  two  compartments  constitute  the  cardiac  division 
of  the  stomach,  and  the  food 
passes  into  them  indifferently 
and  from  one  to  the  other, 
becoming  mixed  and  saturated 
with  the  saliva.  After  enter- 
ing the  stable,  or  while  resting 
in  the  pasture,  the  ox  brings 
up  the  grass  in  little  masses 
and  grinds  it  to  a  pulp  between 
his  powerful  molars,  mixing  it 
at  the  same  time  with  more 
saliva.  He  then  swallows  the 
pulpy  mass,  and  in  this  deglu- 
tition the  stomach  walls  fold 
together,  so  that  the  aliment 
passes  not  into  either  the 
rumen  or  the  reticulum,  but 

directly  into  the  third  stomach,  called  psalterium,  which 
takes  its  name  from  the  leaf-like  folds  of  membrane  that 
line  its  walls.  Through  these  folds  the  broth  is  strained 
into  the  fourth  stomach,  or  rennet-bag,  where  are  ac- 
complished the  phenomena  of  digestion  that  are  com- 
parable to  those  that  take  place  in  animals  having  simple 
stomachs.  At  the  extremity  of  this  last  compartment 
is  the  entrance  to  the  intestinal  canal.  In  the  ruminants 
the  total  length  of  the  intestine  is  more  than  twenty- 
five  times  that  of  the  body. 

Before  describing  the  principal  species  of  ruminants, 
we  must  insist  on  the  importance  of  the  form  of  the  feet 


COMPOUND  STOMACH  OF  AN  ox. 
—a,  oesophagus;  b,  rumen,  or 
paunch  ;  c,  reticulum,  or  second 
stomach  ;  d,  omasum,  or  third 
stomach;  e,  abomasum.or  fourth 
stomach ;  /,  duodenum. 


236 


A    COURSE   ON    ZOOLOGY. 


in  all  the  species  as  a  means  of  classification.  There  are 
only  two  digits,  enclosed  in  a  divided  hoof,  and  the  meta- 
carpal  and  metatarsal  bones,  two  each  in  number,  are 

united      in       single 
bones, 
shank. 


FIG.  169. 


called  the 
That  which 
is  commonly  called 
the  leg  is,  therefore, 
only  a  part  of  the 
hand  or  foot. 

The  ruminants 
have  been  divided 
into  two  groups, 
those  having  horns 
and  those  having 
none  :  among  the 
latter  are  the  camels 
and  llamas.  In  some 
of  the  first  group  the 

horns  are  caducous  or 
STAG,  HIND,  AND  FAWN  (Cervus elaphus).          deciduou8)  falling  off 

every  year,  as  in  the  various  species  of  deer ;  in  others  they 
are  persistent ;  in  the  latter  case  they  may  be  hollow,  con- 
sisting of  a  horny  sheath  covering  an  osseous  prolongation 
of  the  frontal  bone,  as  in  the  ox,  sheep,  and  goat,  or  they 
may  be  solid  and  covered  with  skin,  as  in  the  giraffes. 

Cervidae. — The  deer  family  includes  the  largest  ani- 
mals of  our  forests.  The  red-deer  of  Europe  and  Western 
Asia  stands  over  four  feet  high  at  the  withers,  and  the 
male  has  magnificent  antlers.  It  is  reddish  brown  in 
summer,  and  bluish  gray  in  winter.  The  horns  of  the 
deer  are  purely  osseous,  the  tissue  being  close  and  hard ; 
when  they  have  grown  to  a  certain  size,  the  skin  which 


DEER. 


237 


covers  them  becomes  dry  and  is  rubbed  off,  and  the  bone, 
being  deprived  of  its  covering,  dies  like  any  other  bone 
when  the  periosteum  is  removed.  This  growth  and  fall 
of  the  horns  take  place  every  year,  but  each  year  the 
new  growth  becomes  larger  and  gains  new  branches,  so 
that  it  is  possible  to  tell  the  age  of  a  deer  by  the  develop- 
ment of  its  antlers.  Figure  170  shows  the  growth  of  the 
antlers  in  successive  years. 

FIG.  170. 


ANTLEK  OF  STAG,  showing  increase  in  number  of  prongs  from  first  to  sixth 

year. 

The  wapiti  of  the  Northwestern  United  States  and 
Canada  is  closely  allied  to  the  red-deer  of  Europe ;  it  is 
frequently,  but  improperly,  called  the  elk.  The  fallow- 
deer  is  a  native  of  the  Mediterranean  coasts,  and  has 
been  semi-domesticated  in  Europe,  where  it  is  found  in 
many  parks.  The  horns,  which  are  possessed  by  the 
male  only,  are  cylindrical  at  the  base,  but  flattened  and 
serrated  externally  in  the  remainder  of  their  length. 
This  deer  is  reddish  brown  in  color,  with  white  spots. 

The  roe-deer  or  roebuck  is  a  small  species  of  European 
deer,  its  horns  being  not  largely  developed. 

The  cariacou,  or  Virginia  deer,  is  the  common  deer  of 


238  A   COURSE   ON    ZOOLOGY. 

North  America.  It  is  smaller  than  the  European  red- 
deer,  but  is  more  graceful  in  form  ;  its  height  at  the 
shoulders  is  about  three  feet.  Its  color  is  reddish  brown 
in  summer,  blue  in  autumn,  and  dull  brown  in  winter, 
.the  under  parts  and  internal  surfaces  of  the  legs  being 
white.  The  antlers,  after  curving  backward,  spring 
forward,  their  tips  being  close  together  above  the  nose. 

FIG.  171. 


FALLOW-DEER  (Dama  vulgaris). 

The  coats  of  the  fawns  are  spotted  or  even  striped  with 
white.     The  flesh  of  this  deer  is  exceedingly  palatable. 

The  reindeer,  called  caribou  in  the  United  States,  is 
larger  than  the  Virginia  deer,  and  hardly  as  large  as  the 
stag  or  elk,  but  it  is  more  heavily  built ;  its  legs  are  short 
and  heavy  and  its  hoofs  broad,  giving  it  a  firm  footing 
as  it  runs  over  the  snow.  The  color  is  a  dark  grayish 
brown.  In  Lapland  the  reindeer  has  been  domesticated. 
It  occurs  in  the  Northeastern  United  States  and  Canada 
and  in  the  northern  parts  of  Europe  and  Asia. 


REINDEER. 
FlG.  172. 


239 


k     - 
REINDEER  (Rangifer  tarandus). 


FIG.  173. 


The  elk  or  moose  is  the  largest  of  the  deer  family, 
standing  six  feet  high  at 
the  shoulder.  The  legs  are 
long  and  the  neck  is  short, 
so  that  the  animal  feeds  on 
bushes  and  the  low  branches 
of  trees  rather  than  on 
ground  herbage.  The  horns, 
borne  by  the  male  only,  are 
broad,  flat,  and  branched  ex- 
teriorly, the  internal  edges 
forming  one  curve.  They 
are  solitary  in  their  habits, 
and  prefer  the  wildest  forests. 
A  few  are  found  in  Northern 
Europe  and  Asia,  but  the 
species  is  most  abundant  in  the  colder  regions  of 
North  America. 


HEAD  OP  ELK  (Alces  mcUchis). 


240  A   COURSE   ON   ZOOLOGY. 

Bovidae. — These  are  hollow-horned  ruminants,  the 
horns  being  non-deciduous.  Of  all  animal  species  the 
bovine  is,  without  doubt,  that  which  renders  the  great- 
est service  to  man.  It  is  used  in  ploughing  and  hauling ; 

FIG.  174. 


SHORT-HORN  BULL  AND  cow. 


its  milk  and  flesh  furnish  food ;  its  manure  is  of  great 
value  in  agriculture.     Its  skin,  its  fat,  its  bones,  its  ten- 


FIQ.  175. 


HEREFORD  BULL  AND  cow. 

dons,  and  even  its  intestines  are  made  use  of.  The  skin 
of  the  ox,  the  cow,  and  the  calf  are  turned  into  leather ; 
the  hair  is  used  by  upholsterers,  saddlers,  etc.  Buttons 
and  other  articles  are  made  from  the  bones,  as  are  also 
gelatin  and  bone-black ;  bone-meal  is  also  an  excellent 
fertilizer.  Spoons,  combs,  etc.,  are  made  from  the  horns. 


BUFFALO. 


241 


The  blood  is  used  for  clarifying  syrups,  wines,  etc.,  and 

in  refining  sugar.     From  the  intestines  are  made  strings 

for  musical  instruments,  and  the 

gall  is  used  as  a  eoap  for  clean-  FIG.  176. 

ing  delicate  fabrics. 

Cattle,  like  all  domestic  ani- 
mals, are  greatly  modified  by  the 
influence  of  climate,  food,  and 
habits  of  life.  In  the  temperate 
zones  the  height  is  greater,  the 
flesh  is  more  tender  and  juicy, 
and  the  skin  is  thicker.  North-  JERSEY  cow. 

ern  cattle  furnish  more  and  better 

suet  than  those  of  the  South.     Those  that  live  in  the 
mountains  have  compact  bodies,  very  short  necks,  legs, 

FIG.  177. 


THE  CAPE  BUFFALO  (Bos  caffer). 


and  heads,  the  rump  large,  and  the  horns  projecting 
laterally ;  those  on  the  plains  have  longer  and  more  slen- 
der bodies,  long  legs  and  neck,  and  the  horns  are  directed 

L  q  21 


242 


A   COURSE   ON   ZOOLOGY. 


FIG.  178. 


to  the  front.  While  variations  in  the  species  are  pro- 
duced by  varying  conditions  of  climate  and  surroundings, 
many  of  the  characteristics  have  been  intentionally  de- 
veloped by  selected  breeding.  Thus,  the  short-horns  or 
Durhams  are  entirely  the  result  of  man's  industry. 

Eelated  to  domestic  cattle  are  the  Cape  and  Indian 
buffaloes,  inhabitants  of  Africa  and  Asia,  and  the  bison, 
once  roaming  in  vast  herds  over  the  prairies  of  the 
United  States,  but  now  with  rare  exceptions  seen  only 
in  parks  and  zoological  gardens. 
The  sheep  is  found  wild  only 
in  certain  localities,  these  being 
the  lofty  mountains  of  Central 
Asia  and  Mongolia,  and  the 
Rocky  Mountains  of  the  United 
States.  The  domestication  of 
the  sheep  dates  back  to  pre- 
historic eras,  the  first  peoples 
of  whom  we  have  any  history 
being  pastoral  races,  who  wan- 
dered from  pasture  to  pasture, 
following  their  sheep.  The  sheep  has  perhaps  been  more 
modified  by  man's  influence  than  any  other  animal. 

•    FIG.  179. 


HEAD  OF  THE  ASIATIC  BUFFALO 
(Bubalus  buffelus). 


AMERICAN  BISON. 


SHEEP   AND    GOATS.  243 

The  merino  sheep,  which  originated  in  Spain,  are  widely 
celebrated ;  no  variety  is  more  valuable  for  wool-raising. 


FIG.  180. 


MERINO  SHEEP. 

These  sheep  are  not  large,  and  may  be  recognized  by 
the  small  head  and  slender  legs.  The  wool  is  long  and 
curly,  and  becomes  as  white  as  snow  when  the  animal 
is  washed.  The  feet,  the  muzzle,  and  the  forehead  are 
often  black. 

In  the  sheep  the  horns,  borne  only  by  the  male,  are 
directed  first  backward,  then  curve  downward  and  for- 
ward, forming  a  spiral.  In  the  goats,  both  male  and 
female  have  horns,  and  these  are  turned  upward  and 
backward ;  the  horns  of  the  female  are  small.  Goats 
usually  also  have  beards  on  the  chin,  while  that  of  the 
sheep  is  never  bearded.  There  are  a  number  of  species 
of  goat,  all  of  them  European  or  Asiatic.  They  inhabit 
great  heights  in  the  wildest  mountains,  and  are  timid 
and  wary.  One  of  the  largest  is  the  steinbok,  or  Euro- 
pean ibex, 

The  antelopes  are  closely  allied  to  the  goats ;  most  of 
the  tolerably  large  number  of  species  are  found  only  in 


244 


A   COURSE   ON   ZOOLOGY. 


Africa,  but  some  occur  in  India ;  the  chamois  is  Euro- 
pean,  and  the  Rocky  Mountain  goat  is    found  in  the 


FIG.  181. 


BEZOAR  GOAT  (Copra  xgagrus). 
FIG.  182. 


CHAMOIS. 


United  States.     In  some  species  both  male  and  female 
are  horned,  in  others  only  the  male ;  some  are  almost  as 


ANTELOPES.  245 

large  as  a  horse,  such  as  the  gnu ;  others,  like  the  smaller 
FIG.  183. 


GNU  (Catoblepas  gnu}. 
FIG.  184. 


AFRICAN  GAZELLE. 


African  gazelles,  may  not  exceed  two  feet  in  height  at 
the  shoulder.     The  horns  are  of  various  forms,  usually 

21* 


246 


A  COURSE  ON  ZOOLOGY. 


exceedingly  graceful,  and  sometimes  of  great  length ; 
for  example,  the  gemsbok  is  about  four  feet  high  at  the 
shoulder,  and  its  horns  are  two  and  a  half  feet  long. 
These  animals  are  all  very  active,  very  sure-footed ;  the 
chamois  can  leap  over  a  chasm  fifteen  feet  wide,  or  over 
a  wall  fourteen  feet  high. 

On  the  prairies  of  Western  North  America  is  found 
the  only  known  member  of  a  family  of  ruminants  whose 
horns  are  hollow,  deciduous,  and  having  one  short 
branch.  This  is  the  prong-horn,  and  is  generally  called 
antelope.  It  seems  to  relate  the  cervida}  and  the 
bovidse,  and  the  family  is  called  antilocapridae. 

Giraffidse,  —  The 

FlG-  185- horns  of  the  giraffes 

are  -not  hollow,  but 
solid,  and  consist 
simply  of  processes 
of  the  frontal  bone, 
which  are  covered 
by  the  skin.  These 
horns  are  persistent. 
The  giraffes  are  well 
known  by  their  re- 
markably long  necks 
and  legs,  the  head 
being  eighteen  feet 
above  the  ground. 
They  are  found  in 
Africa. 

GIRAFFE  (Camelopardalis  giraffa).  CamelidSB.  —  This 

family  includes  the 

camels  and  llamas.  They  have  no  horns,  and  they  are 
the  only  ruminants  having  a  pair  of  upper  incisors.  The 


CAMELS.  247 


upper  lip  of  the  camel  is  cleft  and  enlarged ;  the  side  of 
the  foot  is  covered  with  a  thick,  indurated  skin ;  the 


FIG.  186. 


DROMEDARY. 

back  bears  a  lump  of  fat  which  is  single  or  double, 
according  to  the  species.  The  digestive  system  of 
the  camel  differs  from  that  of  the  other  ruminants 
in  that  there  are  but  three  stomachs,  the  psalterium 
being  absent.  The  interior  of  the  paunch  is  lined 
with  large  cells,  and  it  is  said  that  the  camel  can  store 
water  in  these  cells  and  so  go  many  days  without 
drinking. 

There  are  two  species  of  camel :  the  two-humped 
camel  or  Bactrian  camel  of  Central  Asia,  which  is  not 
found  far  from  the  immense  plains  where  dwell  the 


248 


A  COURSE  ON  ZOOLOGY. 

FIG.  187. 


CAMEL  (Camelus  bactrianus). 

Tartars,  and  the  single-humped  camel,  or  dromedary, 

originally    of    Western   Asia, 
FIG.  188.  but  now  domesticated  in  Asia 

and  Africa ;  this  latter  is  the 
species  employed  as  a  beast 
of  burden. 

The  llamas  are  the  American 
representatives  of  the  Camel- 
idse,  true  camels  being  found 
only  in  the  Old  World.  Sev- 
eral species  of  llama  occur  in 
PART  OF  THE  INSIDE  OF  STOMACH-  the  mountainous  regions  of 

PAUNCH  OF  CAMEL,  showing  the    Western  South  America,  and 

water-cells. 

some  of  them  have  been  do- 
mesticated by  the  natives,  both  for  service  as  beasts  of 
burden  and  for  the  long,  woolly  hair  obtained  from  them. 
They  are  much  smaller  than  camels,  and  have  no  humps 
on  the  back. 


HIPPOPOTAMUS. 

FIG.  189. 


249 


LLAMA. 
SUINA. 

This  section  of  the  artiodactyla  includes  the  hippo- 
potamus and  the  various  species  of  suidse.  They  are  not 
ruminants. 

The  hippopotamus  lives  on  the  borders  of  the  large 
rivers  of  Central  Africa  and  in  the  neighboring 
marshes  and  swamps.  It  is  a  large  animal,  attaining  a 
length  of  twelve  feet  or  more ;  though  it  does  not  walk 
well,  it  is  an  agile  swimmer.  Its  diet  is  exclusively  veg- 
etable, and  its  stomach  has  the  enormous  capacity  of 
five  or  six  bushels.  The  feet  have  four  toes,  all  of  which 
have  short,  rounded  hoofs  that  touch  the  ground  in 
walking.  The  incisors  and  canines  grow  continuously, 
like  the  incisors  of  rodents. 


250 


A  COURSE  ON  ZOOLOGY. 


The  suidae,  or  swine  family,  has  a  number  of  represen- 
tatives, among  which  the  more  important  are  the  wild 


FIG.  190. 


HIPPOPOTAMUS  AMPHIBIUS. 
FIG.  191. 


WILD  BOAR. 


boar  of  Europe,  Asia  Minor,  and  Northern  Africa,  the 
wart-hog  of  Southeastern  Africa,  and  the  peccary, 
which  is  found  from  Arkansas  to  South  America.  These 


SWINE. 


251 


animals  live  either  solitarily  or  in  families  in  forests  and 
swamps.  The  canines  of  the  wild  boar  are  developed 
enormously,  being  curved  forward  and  upward,  and 
forming  tusks  that  are  powerful  weapons.  All  the  mem- 
bers of  this  family  have  elongated  mobile  snouts,  which 
are  used  in  digging  in  the  soil  for  the  roots  that  consti- 
tute their  food.  There  are  four  toes  on  each  foot,  only 
three  of  which  touch  the  ground  in  walking. 

FIG.  192. 


IMPROVED  YORKSHIRE  PIGS. 

The  domestic  hogs  are  descendants  of  the  wild  boar ; 
there  are  a  large  number  of  varieties,  all  developed  by 
careful  breeding,  some  of  which  become  very  fat,  while 
others  are  valued  for  their  lean  meat.  Among  them  we 
may  name  the  Essex,  Sussex,  Berkshire,  Yorkshire,  and 
Victoria  varieties ;  from  these  mainly  the  American 
hogs  are  descended. 


252 


A  COURSE  ON  ZOOLOGY. 


CHAPTER  XXVI. 
Proboscidia — Perissodactyla. 

THE  elephants  are  the  largest  terrestrial  mammals. 
There  are  two  species,  the  Indian  and  the  African.  The 
Indian  or  Asiatic  elephant  is  usually  taller  than  the 


FIG.  193. 


AFRICAN  ELEPHANT  ("Jumbo"). 

African,  and  has  smaller  ears  and  tusks,  and  a  concave 
forehead.  It  inhabits  the  forests  of  continental  India 
and  of  Ceylon,  Sumatra,  and  Borneo.  It  is  domesti- 
cated, and  trained  to  do  many  kinds  of  work.  The 


ELEPHANTS.  253 

African  elephant  has  a  convex  forehead ;  it  is  not  now 
FIG.  194. 


Heads  of  (A)  African  and  (B)  Indian  Elephants. 

domesticated,  and    has   not   been  for  many  centuries. 

This  animal  is  destructively 

hunted  for  its  tusks,  which  FlG  195- 

furnish  the  valuable  ivory 

of  commerce. 

The  two  enormous  spe- 
cies of  fossil  mammals 
known  as  mammoth  and 
mastodon  belonged  to  the 
class  proboscidia,  and  differed  but  little  from  the  ele- 
phants in  organization  and  in  habit. 

PERISSODACTYLA. 

The  perissodactyla   are  classified   in   three   families, 
represented  by  the  horse,  the  tapir,  and  the  rhinoceros. 

22 


254  A   COURSE   ON   ZOOLOGY. 

The  horse,  asses,  zebras,  and  quagga  make  up  the 
family  equidae ;  their  feet  terminate  in  single  toes 
protected  by  but  one  hoof.  They  are  all  herbivorous, 
and  the  digestive  apparatus  is  simple  ;  they  do  not  rumi- 
nate. 

As  we  know  the  horse,  he  is  the  result  of  intelligent 
breeding,  continued  for  centuries,  and  directed  to  render 
this  valuable  servant  better  adapted  to  fulfil  the  func- 
tions for  which  man  designs  him.  The  wild  horse — that 
is,  in  a  natural  state  and  neither  raised  nor  broken  by 
man — is  smaller  than  the  domestic  horse  ;  it  has  long, 
coarse  hair,  a  large  strong  head,  projecting  bones ;  but 
delicate,  well-formed  limbs. 

The  jaws  of  the  horse  are  provided  with  teeth  which 
are  worthy  of  study :  at  the  back  of  the  mouth  are  the 
large  square  molars  which  are  used  to  crush  and  grind 
grains,  straw,  and  fodder ;  they  are  twenty-four  in  num- 
ber, twelve  on  each  side,  six  above  and  six  below.  In 
front  are  flat  teeth  with  sharp  edges,  used  in  cropping 
herbage ;  they  are  the  incisors,  and  number  twelve,  six 
above  and  six  below.  Between  the  molars  and  incisors, 
above  and  below  and  on  each  side,  is  a  space  without 
teeth,  and  where  the  gums  are  naked.  This  is  the  space 
in  which  lies  the  bit,  and  it  is  called  the  bar.  Usually, 
each  jaw  of  the  male  has  two  dog-teeth,  which  represent 
the  canines  of  the  carnivora,  and  are  placed  in  front  of 
and  at  a  little  distance  from  the  molars. 

In  our  days  the  true  wild  horse  seems  to  have  disap- 
peared ;  nevertheless  in  those  parts  of  both  continents 
known  as  steppes,  savannas,  pampas,  and  prairies  are 
found  horses  that  have  been  untamed  and  independent 
for  several  generations,  being  descendants  of  domestic 
horses  that  have  escaped  or  become  lost;  these  wild 


THE    HORSE. 


255 


horses    may   be   considered    as    representative   of    the 
original  wild  race. 

There  are  many  varieties  of  horse,  some  characterized 
by  strength,  others  by  swiftness.  The  large,  short,  and 
heavily-built  horses  are  adapted  for  slow  work  that 
requires  sustained  effort.  The  Flemish  and  Norman 
horses  are  such,  and  are  greatly  valued  for  heavy  work  ; 
so,  also,  are  the  Percherons.  The  Andalusian  horses  of 

FIG.  196. 


DENTITION  OP  THE  HORSE,  AS  A  WHOLE.— P,  pincers ;  M,  intermediates  ;  C, 
corners;  Cr,  canines;  AM,  supplementary  premolars;  MC,  deciduous 
molars  or  premolars  ;  MP,  permanent  molars. 

Spain  have  long  been  celebrated  for  their  grace  and 
fleetness.  The  Arabian  horses  have  in  the  Orient  pre- 
served all  their  purity  and  their  primitive  excellence. 
Among  the  tribes  that  inhabit  the  desert  the  horse  is 
more  than  a  servant,  it  is  a  companion,  and  to  this 
necessity  must  be  attributed  the  superiority  of  the  Ara- 
bian horses.  There  is  a  very  similar  variety  in  Algeria, 
direct  descendants  of  the  Numidian  horses,  which  an- 


256  A   COURSE   ON    ZOOLOGY. 

ciently  had  great  celebrity.  These  horses  are  docile, 
gentle,  patient,  and  courageous,  sure-footed  on  difficult 
ground,  indefatigable ;  they  combine  all  the  characters 
required  in  army  horses. 

In  agriculture  the  horse  is  the  most  active  and  most 
valuable  aid  to  man.  Even  when  it  is  dead  its  carcass 
has  a  considerable  value  ;  the  hide,  flesh,  blood,  fat,  bones, 
hair,  mane  and  tail,  hoofs, — all  can  be  utilized.  In  cer- 
tain countries  horse-meat  is  eaten,  and  there  is  no  pos- 
sible objection  to  the  use  of  this  meat  as  food  if  the 
animal  be  killed  when  in  a  healthy  condition.  Horses 
killed  by  accident  might  well  be  eaten,  but  it  would  not 
be  profitable  to  raise  horses  for  food. 

The  species  of  ass  include  the  domestic  ass  and  the 
African  and  Asiatic  wild  asses.  The  domestic  ass  is  a 
descendant  of  the  African ;  the  Asiatic  species  is  light 
in  color,  and  has  a  dark  stripe  in  the  middle  of  the  back, 
extending  from  neck  to  tail.  "  On  comparing  the  ass  to 
the  horse,  both  in  form  and  general  aspect,  we  notice  at 
once,"  says  Daubenton,  "  that  the  ass's  head  is  larger  in 
proportion  to  the  body  than  that  of  the  horse ;  the  ears 
are  much  longer,  the  forehead  and  temples  furnished 
with  longer  hair,  the  eyes  less  prominent,  and  the  lower 
eyelid  flatter ;  the  upper  lip  is  more  pointed  and  over- 
hanging, the  neck  and  shoulders  are  thicker,  the  withers 
are  higher,  the  chest  is  narrower  and  blended  with  the 
throat.  The  back  is  convex,  and  usually  the  spinal 
column  is  prominent  from  its  origin  to  the  base  of  the 
tail ;  the  haunches  are  higher  than  the  withers ;  the 
rump  is  flat  and  hanging ;  the  long  hairs  of  the  tail  are 
confined  to  the  last  quarter  of  its  length."  The  mane 
of  the  ass  is  erect,  not  flowing  like  that  of  the  horse. 

The  mule  is  the  result  of  crossing  the  horse  and  the 


PERISSODACTYLA.  257 

ass,  and  preserves  some  of  the  features  of  each.     To  the 
FIG.  197. 


ASINUS  QUAGGA  (from  a  photograph  by  Messrs.  York  &  Son,  London). 

ass  it  owes  its  large  head,  long  ears,  and  vigorous  temper- 
ament ;  to  the  horse  its  height,  its  elegant  outlines,  and 
r  22* 


258 


A   COURSE   ON   ZOOLOGY. 


its  greater  activity.  The  mule  is  more  sedate  than  the 
horse  and  stronger  than  the  ass ;  it  supports  heat  better 
than  the  first,  and  cold  better  than  the  second,  and  is  a 


FIG.  199. 


RHINOCEROS  UNICORNIS  (from  a  photograph  by  Gambier  Bolton,  F.Z.S.). 

valuable  animal  in  mountainous  countries  on  account  of 
its  firmness  of  foot. 

The  zebras  are  smaller  than  the  horse  and  larger  than 
the  ass,  resembling  the  latter  in  outline  and  proportions. 


CETACEA.  259 

Their  entire  bodies  are  very  regularly  striped  with  alter- 
nate white  and  black  or  brown  bands.  They  are  found 
in  South  Africa,  as  is  also  the  quagga,  which  resembles 
the  ass  still  more  closely  than  does  the  zebra. 

The  tapir  has  a  long,  pointed  head,  the  nose  being 
elongated  into  a  sort  of  trunk.  It  is  a  semi-aquatic 
animal,  of  peaceful  disposition,  living  in  herds  in  India 
and  South  America. 

The  rhinoceros  is  heavy  and  compact  in  form,  the 
body  being  covered  with  an  almost  impenetrable  skin, 
which  forms  folds  having  the  appearance  of  jointed 
armor.  They  possess  enormous  force,  and  are  brutal 
and  fierce  without  intelligence.  They  are  herbivorous. 
There  are  several  species  found  in  Asia  and  Africa,  some 
having  two  horns,  some  only  one. 


CHAPTER  XXVII. 
Cetacea  and  Sirenia. 

THE  cetacea  are  classified  in  two  suborders,  the  odon- 
toceti,  or  toothed  whales,  including  the  dolphins,  por- 
poises, and  cachalots,  and  the  mystacoceti,  which  have 
no  teeth  in  the  adult  state,  but  whose  palates  are  pro- 
vided with  plates  of  whalebone.  Both  are  carnivorous. 

Odontoceti. — Dolphins  are  very  carnivorous ;  they  fol- 
low, in  large  schools,  transatlantic  steamers,  devouring 
the  fish  that  are  attracted  by  the  debris  continually 
thrown  overboard.  They  may  attain  a  length  of  ten 
feet. 

The  porpoise  has  a  shorter  snout  than  the  dolphin,  and 


260 


A   COURSE   ON   ZOOLOGY. 


is  much  smaller.     It  is  gregarious,  and  many  are  often 
seen  swimming  in  file,  their  backs  appearing  alternately 


FIG.  201. 


COMMON  DOLPHIN  (Delphinusdelphis). 


above  the  water.     Its  teeth,  like  those  of  the  dolphin, 
are  admirably  adapted  for  catching  fish. 


FIG.  202. 


PORPOISE  (Phocaena  communis). 


The  cachalot,  or  sperm  whale,  grows  as  long  as  fifty  or 
sixty  feet ;  it  has  teeth  only  in  the  lower  jaw.  Its  head 
is  enormous,  forming  one-third  the  length  of  the  body. 


WHALES. 


261 


From  these  animals  is  obtained  spermaceti,  a  white,  crys- 
talline substance,  that  is  found  in  the  right  nostril  under 
the  skin,  and  in  front  of  the  cranial  bones,  and  in  such 
large  quantity  that  a  single  whale  will  furnish  several 
hogsheads.  The  cachalot  also  yields  ambergris,  an  odor- 
ous substance  used  in  perfumery.  It  appears  to  be  pro- 
duced from  the  bile.  The  oil  of  the  sperm  whale  is 
highly  prized. 

Mystacoceti. — The  true  whales  are  gigantic  animals, 
measuring   eighty   or  eighty-five   feet   in   length,   and 

FIG  203. 


WHALE. 


weighing  as  much  as  one  hundred  and  fifty  tons.  The 
general  form  is  like  that  of  a  fish,  the  body  being  long 
and  cylindrical,  tapering  towards  the  tail  and  joined 
directly  to  the  head  without  any  appearance  of  a  neck. 
The  head  is  very  large,  the  mouth  opening  exceedingly 
wide,  being  carried  back  under  the  eyes,  which  are  very 
small  in  proportion  to  the  size  of  the  body,  and  placed 
very  low,  near  the  commissure  of  the  lips.  The  jaws 


262  A   COURSE    ON    ZOOLOGY. 

have  no  teeth,  those  organs  being  replaced  by  fibrous 
plates,  with  which  each  side  of  the  mouth  is  provided, 
and  formed  of  the  blackish  elastic  substance  commonly 
called  whalebone.  These  plates,  from  eight  to  ten  inches 
wide  and  as  much  as  ten  feet  long,  are  rooted  in  the 
upper  jaw,  and  have  together  the  appearance  of  an 
enormous  comb.  Whales  have  two  anterior  limbs,  com- 
posed of  the  same  bones  that  form  the  corresponding 
limbs  of  large  terrestrial  animals,  but  only  the  hand  is 
outside  of  the  body,  and  the  phalanges,  instead  of  being 
free,  are  blended  into  a  fin.  There  are  no  posterior  limbs, 
and  the  body  terminates  in  a  crescent-shaped  tail,  which 
is  horizontal,  instead  of  being  vertical,  like  a  fish's  tail. 

The  respiration  of  whales  is  aerial;  they  have  lungs, 
and  respire  the  air  itself,  so  that  although  they  live  en- 
tirely in  the  water,  they  are  obliged  to  come  frequently 
to  the  surface  to  breathe.  Like  other  mammals,  they 
are  warm-blooded.  They  bring  their  young  into  the 
world  alive, — not  by  eggs,  like  fish, — and  they  suckle 
their  young.  Their  skin  is  not  scaly,  but  a  hard  hide, 
more  than  an  inch  thick,  under  which  is  a  layer  of  fatty 
tissue.  This  skin  is  black  on  the  back,  and  grayish  or 
silver  below.  Whales  feed  on  crustaceans,  mollusks,  and 
small  fish ;  when  they  open  their  enormous  mouths,  the 
mass  of  water  that  enters  necessarily  contains  myriads 
of  small  creatures ;  in  order  to  collect  them  and  get  rid 
of  the  water,  this  latter  is  filtered  out  through  the  comb 
formed  by  the  whalebones. 

Whales  do  not  leave  the  water,  and  only  rarely  the 
deep  sea ;  their  organization  does  not  allow  them  to 
come  on  land,  and  their  weight  and  size  prevent  them 
from  approaching  the  shores.  When  they  are  driven  on 
shore  by  storm,  they  are  stranded  just  like  ships,  and 


MANATEES  AND  DUGONGS.  263 

enormous  specimens  of  this  and  allied  species  are  some- 
times so  thrown  on  our  coasts. 

The  substances  obtained  from  the  whale  are,  first,  the 
oil  which  is  obtained  by  melting  the  fat  or  blubber,  and 
a  single  whale  may  yield  eight  or  ten  tons ;  then  the 
whalebone,  which  is  used  for  many  purposes. 

The  arctic  right  whale  is  forty-five  or  fifty  feet  long, 
as  is  also  the  humpback,  so  called  from  the  shape  of  the 
dorsal  fin.  The  name  balaenoptera  is  given  to  the  razor- 
backs,  fin-backs,  and  rorquals,  which  latter  are  the  largest 
species.  The  balsenoptera  have  folds  in  the  skin  of  the 
throat,  and  very  distinct  dorsal  fins. 

SIRENIA. 

This  order  contains  but  two  living  families,  the  mana- 
tees, or  sea-cows,  and  the  dugongs.  They  are  found  in 


DUGONG  (Halicore  dugong). 


warm  Southern  seas  and  estuaries ;  they  are  inoffensive, 
gregarious,  and  herbivorous.  Like  the  cetacea,  they 
have  no  hind  limbs,  but  the  phalanges  of  the  fore  limbs 
are  perfect  in  sirenia,  and  there  are  rudimentary  nails. 


264  A   COURSE   ON   ZOOLOGY. 

The  dugongs  attain  a  length  of  about  ten  feet ;  the  mana- 
tees are  somewhat  longer.  In  both  families  the  female 
displays  a  remarkable  affection  for  her  young,  carrying 
it  around  under  the  nippers,  with  the  head  out  of  water. 
The  tail  of  the  manatee  is  rounded  at  the  end ;  that  of 
the  dugong  is  fluked.  The  manatee  partly  leaves  the 
water,  even  feeding  on  shore  plants ;  the  dugong  keeps 
to  the  water,  grazing  on  algae. 


CHAPTER  XXVTII. 
Marsupials — Monotremes. 

THE  females  of  the  marsupials  have  the  mammae  placed 
in  a  sac  or  pocket  (Latin  marsupium),  in  which  the  young 
are  placed  after  birth.  This  organization  is  necessary, 
because  the  young  are  born  in  a  very  imperfect  condition, 
and  must  remain  suspended  at  the  mammae  during  a 
certain  term.  The  sac  is  supported  by  special  bones, 
called  marsupial  bones,  which  are  processes  from  the 
anterior  portion  of  the  pelvis  ;  they  exist  in  the  male  as 
well  as  in  the  female.  The  only  species  that  we  need 
study  are  the  kangaroos  and  opossums. 

The  kangaroos  live  in  herds  on  the  borders  of  the  great 
forests  of  Australia.  There  are  several  species  of  diifer- 
ent  sizes,  the  largest  sometimes  attaining  a  height  of 
eight  feet.  The  fore  limbs  are  much  shorter  than  the 
posterior,  and  the  latter,  protected  by  a  sort  of  hoof,  are 
the  only  ones  used  in  locomotion,  which  in  these  animals 
is  very  curious,  consisting  of  a  series  of  jumps.  The  long 
tail,  whose  bones  are  very  strong,  acts  as  a  sort  of  spring 


MARSUPIALS. 


265 


assisting  in  the  jumping.     These  animals  are  peaceable 
and  inoffensive,  entirely  herbivorous;  they  are  hunted 


FIG.  205. 


THE  GREAT  KANGAROO  (Macropus  giganteus). 

both  for  their  skins,  which  make  excellent  leather,  and 
for  their  flesh. 

The  opossums  are  the  American  representatives  of  the 
marsupials ;  there  are  several  species,  some  of  the  South 
American  being  scarcely  larger  than  a  mouse.  That  of 
North  America,  the  Virginia  opossum,  is  larger  than  a 
cat ;  it  has  a  scaly  prehensile  tail,  and  is  nocturnal  in  its 
habits,  which  are  those  of  a  scavenger. 

There  are  many  other  marsupials,  and  we  may  mention 
as  among  the  most  curious  the  flying  phalangers,  which 
have  a  membrane  stretching  from  the  outer  digit  of  the 
M  23 


266 


A   COURSE   ON    ZOOLOGY 
FlG.  206. 


VIKGINIAN  OPOSSUM  (Didelphys  virginiano). 
FIG.  207. 


1,  FLYING  PHALANGER  (Petaurus  taguanoides). 

2,  FLYING  MOUSE  (Petaurus  pygmseus). 

fore  paw  to  the  foot ;  by  the  aid  of  this  membrane  they 
can  make  enormous  leaps  from  tree  to  tree. 


MONOTREMES. 


MONOTREMATA. 


267 


This  order  contains  but  few  species,  mostly  limited  to 
Australia  ;  and  in  it  we  find  a  sort  of  transition  from 
mammals  to  birds.  In  fact,  the  shoulder  of  the  mono- 
tremes  has  the  same  structure  as  that  of  birds  and  rep- 
tiles ;  their  urinary  system  is  like  that  of  birds,  and  their 
teeth  are  either  shed  early  in  life  or  entirely  absent. 
There  are  no  mammae,  the  mammary  glands  opening 
directly  on  the  surface  of  the  skin ;  and  the  female  lays 

FIG.  208. 


ORNITHOKHYNCHUS  PARADOXUS. 

eggs,  from  which  the  young  are  hatched,  thus  differing 
from  all  other  mammals. 

The  ornithorhynchus  is  the  most  interesting  of  this 
order.  By  the  Australian  colonists  it  is  called  water- 
mole.  Its  teeth  drop  out  before  it  reaches  adult  life, 
leaving  on  each  side  of  the  jaw  two  horny  prominences, 
which  serve  the  purposes  of  mastication  in  the  adult. 
The  mouth  is  surrounded  with  naked  skin,  which  forms 
folds  at  its  base,  and  looks  much  like  the  bill  of  a  duck. 
The  length  is  eighteen  to  twenty  inches  from  tip  to  tip, 
and  the  body  is  covered  with  short,  soft  fur.  The  animal 


268 


A   COURSE   ON    ZOOLOGY. 


FIG.  209. 


is  aquatic  in  its  habits ;  its  food  consists  of  worms,  crus- 
taceans, and  water  insects. 

The  echidna  is  sometimes  called  spiny  ant-eater,  for 

it  lives  mainly  on  ants. 
It  has  a  long-pointed 
muzzle,  and  the  fur 
of  the  back  is  inter- 
spersed with  strong 
spines  about  two 
inches  long.  It  can 
burrow  very  rapidly 
in  soft  earth.  There 
are  several  varieties 
ECHIDNA  ACULEATA.  of  this  creature  found 

in     the     rocky     and 

mountainous  regions  of  New  Guinea,  Tasmania,   and 
Australia. 


CHAPTER   XXIX. 
Birds. 

THE  classification  of  birds  does  not  rest  on  a  satis- 
factory basis  like  that  of  mammals.  All  living  birds  are 
divided  into  two  subclasses,  the  ratitae,  or  flat-breasted 
(raft-breasted)  birds,  which  is  small  in  'number,  and  the 
earinatae,  or  keel-breasted  birds,  which  includes  all  the 
others. 

RATITAE. 

The  wings  of  these  birds  are  short  or  rudimentary, 
and  are  not  adapted  for  flying ;  the  breastbone  is  flat, 


269 


OSTRICH  (Struthio  cantelus). 
23* 


270 


A  COURSE  ON  ZOOLOGY. 


not  requiring  large  surfaces  for  muscles  of  flight,  as  in 
the  carinatse.     There  are  no  shafted  feathers. 

The  smallest  representative  is  the  apteryx  or  kiwi  of 
New  Zealand, — usually  not  much  larger  than  a  good-sized 
hen.  The  largest  is  the  ostrich,  which  is  also  the  largest 
living  bird,  being  six  or  seven  feet  high.  The  plumage 
of  the  males  is  black  mixed  with  white,  and  there  are 

FIG.  212. 


CASSOWARY  (Casuarius  galeaius). 

large  white  feathers  on  the  wings  and  tail ;  that  of  the 
female  is  uniform  gray.  The  ostrich  is  now  found  wild 
only  in  the  sandy  portions  of  Africa,  Arabia,  and  Syria, 
but  it  is  tamed  and  reared  on  ostrich  farms  for  the  feath- 
ers, which  have  great  value.  The  ostrich  can  run  with 
great  rapidity,  and  can  travel  over  the  desert,  passing 
rapidly  from  one  oasis  to  another  in  search  of  food. 
The  rhea  of  South  America  is  closely  related  to  the 


BIRDS.  271 

ostrich,  but  is  not  as  large,  and  its  grayish  feathers  have 
no  commercial  value.  The  emu  and  the  cassowary  are 
found  in  Australia  and  the  South  Sea  Islands ;  they  are 
three  or  four  feet  high.  The  cassowary  has  a  horny 
crest  on  the  forehead  ;  the  emu  has  none ;  otherwise  the 
birds  are  very  similar. 

CARINATAE. 

The  following  classification  of  the  carinatae,  the  birds 
with  a  keeled  breastbone,  is  mainly  that  of  Itidgway  s 
"  North  American  Birds :" 

99  *   -  1.  PYGOPODES.— Divers :  loon,  penguin,  auk. 

2.  LONGIPENNES.— Gulls  and  terns. 

3.  TUBINARES.— Nostrils  open  at  end  of  nasal  bones :  albatross,  petrels. 

4.  STEGANOPODES. — Toes  all  webbed  completely :  cormorant,  pelican. 

5.  ANSERES. — Ducks,  geese,  swans. 

6.  ODONTOGLOSS^E.  —Flamingoes. 

7.  HERODIONES.— Herons,  ibis,  storks. 


8.  PALUDICOL^E.— Cranes,  rails,  coots. 

9.  LIMICOL.E.— Plover,  snipe,  woodcock. 

10.  GALLING.— Chickens,  partridge,  quail,  turkey,  pheasant. 

11.  COLUMB.S:.— Pigeons  and  doves. 

12.  RAPTORES.— Eagles,  hawks,  vultures,  buzzards. 

13.  PSITTACI.— Cockatoos,  parrots,  paroquets. 

14.  COCCYGES.— Cuckoo. 

15.  PICI.— Woodpeckers,  flicker. 

16.  MACROCHIRES.— Goat-suckers,  whippoorwill,  humming-birds. 

17.  PASSERES.— Perching  birds. 

SWIMMING   AND   DIVING   BIRDS. 

The  orders  of  swimming  and  diving  birds  are  related 
only  by  the  aquatic  habits  common  to  all.  The  feet  are 
webbed  or  palmated  more  or  less  perfectly,  according  to 
the  order.  The  plumage  is  covered  with  a  sort  of  fatty 
varnish  that  makes  it  impermeable  to  water ;  under  the 
feathers  is  an  exceedingly  soft  and  thick  down  that 
protects  the  body  from  cold ;  the  neck  is  more  or  less 


272 


A   COURSE   ON   ZOOLOGY. 


elongated ;  the  legs,  on  the  contrary,  are  short.  Some, 
such  as  the  albatross,  have  powerful  wings,  adapted  for 
rapid  flight ;  others,  like  the  penguin,  cannot  fly  at 
all,  but  the  rudimentary  wing  is  used  as  an  aid  in 
swimming. 
Pygopodes. — The  legs  are  inserted  far  behind,  giving 

FIG.  213. 


KING  PENGUIN  (Aptenodytes  pennantii). 


the  body  a  vertical  position  when  standing,  and  the  bird 
cannot  walk  well ;  the  tail-feathers  are  absent  or  very 
short.  The  penguins  are  the  largest  of  this  order,  stand- 
ing as  high  as  four  feet.  They  are  found  in  Antarctic 
and  South-Temperate  regions,  and  pass  more  than  six 
months  of  the  year  on  the  sea,  approaching  the  shores 
only  at  the  breeding  season,  and  remaining  there 
during  the  incubation  of  the  eggs  and  the  rearing  of 
the  young.  The  wings  are  only  a  sort  of  flippers  cov- 
ered with  scale-like  feathers,  and  they  are  often  consid- 
ered as  a  distinct  order  called  "Impennes,"  They  are 


BIRDS. 


273 


very  awkward  on  land.     The  auks  now  living  are  small 

and  confined  to  the  arctic  regions.       The   great   auk, 

which    was     three    feet 

high,  much  resembled  the 

penguin,  but  is  believed 

to  be   extinct   since  the 

middle   of     the    present 

century.      The  loons    or 

divers     are   common   in 

the    northern    parts    of 

both    continents.     They 

have    a     peculiar    wild, 

shrill,  and  howling  cry. 

Longipennae.  —  The 
birds  of  this  group,  the 
gulls  and  terns,  have 
long  arid  powerful  wings, 
which  form  when  spread 
a  narrow  flexible  band. 
The  legs  are  set  in  about 
the  middle  of  the  body,  which  is  horizontal  when  stand- 
ing. All  pass  a  great  part  of  the  time  suspended  be- 
tween the  sky  and  the  sea,  and  they  are  found  hundreds 
of  miles  from  any  land.  They  follow  ships  in  large 
numbers,  seeking  either  the  debris  of  food  thrown  over- 
board or  the  fishes  attracted  by  this  debris.  There  are 
many  species. 

Tubinares. — This  order  includes  the  species  of  albatross 
and  petrel.  The  albatross  is  three  or  four  feet  in  total 
length,  and  is  found  principally  in  Southern  seas,  though 
the  black-footed  albatross  is  abundant  on  our  Pacific 
coasts.  It  frequently  follows  ships  far  out  at  sea,  as 
does  also  the  stormy  petrel,  or  Mother  Carey's  chicken, 


GREAT 


NORTHERN     DIVER 

glacialis). 


(Colymbi 


274  A   COURSE   ON   ZOOLOGY. 

which  is  the  best  known  of  the  petrel  family,  and  is  the 

\ 

FIG.  215. 


ALBATROSS. 


PIG.  216. 


STORMY  PETREL  (Procellaria  pelagica). 


smallest  web-footed  bird  known,  being  not  much  larger 
than  a  lark.     Sailors  consider  the  appearance  of  the 


275 


CORMORANT 
FIG.  218. 


PELICAN  (Pelecanus  onocrotalus). 


276 


A   COURSE   ON    ZOOLOGY. 


stormy  petrel  as  an  omen  of  storm,  for  they  are  seldom 
seen  unless  disturbed  by  high  seas. 

Steganopodes. — In  this  order  the  toes  are  completely 
webbed.     The  cormorant  lives  on  islands  in  most  parts 


.  219. 


SWAN. 


of  the  world.  Its  head  is  rather  small,  and  is  naked 
below  the  eyes  and  at  the  root  of  the  beak.  The 
pelicans  have  under  their  enormous  beak  a  membranous 
pouch  in  which  they  can  store  their  prey  until  at  liberty 
to  swallow  it  leisurely.  They  are  found  principally 
in  warm  countries,  and  frequent  both  fresh  and  salt 
waters,  where  they  unite  in  flocks  for  fishing.  The 
cormorants  also  have  a  pouch,  much  less  developed 
than  that  of  the  pelicans.  Among  the  steganopodes 
are  the  tropic  birds  and  the  man  o'  war,  or  frigate  bird, 


BIRDS.  277 

frequently  seen  in  the  Gulf  of  Mexico  and  in  the  tropical 
oceans. 

Anseres, — This  order  has  short  legs,  and  the  cutting 
edges  of  the  bill  are  more  or  less  fringed  or  serrated. 

FIG.  220. 


FLAMINGO  (Phcenicopterus  ruber). 

The  species  are  exceedingly  numerous ;  among  the 
ducks  we  may  cite  the  teal,  wood  duck,  black  duck, 
mallard,  red-head,  and  canvas-back.  They  all  have 
wide,  flat  beaks,  and  the  legs  are  placed  back  of  the 
centre  of  the  body ;  the  neck  is  long,  but  not  as  long  as 
that  of  the  goose,  while  that  of  the  swan  is  very  long. 
The  eider  is  a  northern  species  that  rarely  descends  as 
far  south  as  our  coasts.  Its  body  is  protected  by  a  very 
close  and  very  soft  down,  which  is  highly  prized  for 
stuffing  pillows,  etc.  The  general  characters  of  the  goose 
are  well  known.  It  swims  little,  and  does  not  dive.  The 

24 


278 


A  COURSE  ON  ZOOLOGY. 


larger  wild-geese  are  almost  three  feet  long.  The  swans 
are  remarkable  for  their  elegance  of  form  and  grace  of 
movement. 

Odontoglossae. — The  flamingo  has  a  tongue  whose  sides 
and  base  are  covered  with  horny  spines.  They  can  swim 
in  deep  water,  but  the  legs  are  rather  adapted  for  wading 
than  for  swimming.  One  European  species,  when  erect, 
stands  about  six  feet  high. 

Herodiones. — Like  the  flamingoes,  most  of  the  birds  of 

FIG.  221. 


COMMON  HERON  (Ardea  cineretf). 

this  order  have  very  long  legs,  and  the  lower  parts  of 
the  thighs  are  without  feathers.  The  length  of  leg  is 
compensated  for  by  the  great  length  of  the  neck  and 
bill,  by  which,  without  stooping,  the  bird  can  pick  up 
from  the  level  of  its  feet  the  reptiles,  insects,  and  fish 


BIRDS. 


279 


FIG.  222. 


on  which  it  feeds. 
Usually  the  toes  are 
very  long,  and  partially 
joined  by  a  membrane, 
so  that  the  weight  of  the 
bird  can  be  supported 
by  soft  and  muddy  bot- 
toms. There  are  a 
number  of  species  of 
heron,  distinguished 
principally  by  their  size 
and  color.  Their  long 
bill  opens  almost  up  to 

the    eyes,   18    sometimes          BOAX-KU.  (Oanerima  cocMearia). 

serrated,  and  is  used  for 

catching  the  fish  and  frogs  which  form  their  habitual 

FIG.  223. 


CEANE  (Qrus  cinerea). 

food.     When,  however,  the  fishing  is  poor,  the  heron  eats 
worms,  mollusks,  and  reptiles.     The  ibis  and  stork  were 


280  A   COURSE   ON   ZOOLOGY. 

considered  sacred  by  the  Egyptians.  A  species  of 
stork  found  in  India  carries  on  its  neck  an  immense 
pouch,  much  larger  than  that  of  the  pelican.  The 
boat-bill  differs  from  the  herons  by  its  curious  boat- 
shaped  bill. 

Paludicolae. — The  cranes,  rails,  and  coots  are  not  as 
aquatic  as  the  preceding  birds ;  a  considerable  propor- 
tion of  their  food  consists  of  vegetable  substances.  The 
Virginia  rail  and  the  water-rail  are  esteemed  as  food. 

FIG.  224. 


WATER-KAIL  (Battue  aquations). 

The  moor-hen  and  the  corn-crake  are  closely  allied  to  the 
water-rail.  These  birds,  though  comparatively  small, 
are  rapid  runners. 

Limicolae,— The  various  species  of  plovers,  woodcocks, 
snipes,  sand-pipers,  and  the  stilts,  curlews,  and  willets 
belong  to  this  order.  These  birds  frequent  low,  moist 
grounds,  and  feed  on  worms,  insects,  larvae,  and  mollusks. 
They  have  long  bills  with  which  to  seek  their  food  in 
the  mud  and  marshes,  and  the  sand-pipers,  curlews,  and 
several  species  of  snipe  feed  on  the  small  insects  left  on 
the  sea-shore  at  the  ebb  of  the  tide. 

Gallinse.  —  This  order  includes   the   more  important 


BIRDS. 


281 


birds  used  as  food ;  they  are  heavy  birds,  and  do  not 
fly  easily.  Their  toes  are  not  adapted  for  grasping 
branches  nor  for  swimming  nor  wading,  but  for  flat 
surfaces,  and  they  live  almost  entirely  on  the  ground, 
ordinarily  in  little  flocks,  composed  of  one  male  and 
several  females.  Most  of  the  varieties  are  of  foreign 
origin,  but  they  readily  acclimate  themselves  in  all 


FIG.  225. 


FIG.  226. 


1,  RINGED  PLOVER  ;  2,  GRAY  PLOVER  ; 
3,  GOLDEN  PLOVER. 

Countries.        The    most    im-  FEET  OF  VARIOUS  BIRDS.— a,  swift ;  6, 
n    11  •     ,1        i  •   i  stilt;  c,  black  stork :  d,  wryneck  ;  e, 

portant  of  all  is  the  chicken,  falcon .'  /( raven .  ;,  k'ingflysher ;  *, 
which  we  have  sufficiently  peiicau ;  *,  grebe ;  k,  coot;  i,  smew- 
described  in  a  previous  chap- 
ter. The  chickens  of  our  rural  districts  are  usually  so 
mixed  in  form,  plumage,  and  size  that  no  distinct  race 
is  determinable  ;  when  pure  races  are  to  be  bred  they 
must  be  kept  apart.  The  turkey  is  a  native  of  North 
America.  The  pheasants  are  natives  of  Asia,  and  have 

24* 


282 


A   COURSE   ON    ZOOLOGY. 


been  introduced  and  acclimated   in  all  the  temperate 
regions  of  Europe,  and  attempts  have  been  made  to  in- 

FIQ.  227. 


COMMON  PHEASANT  (Phasianus  colchicus),  male  and  female. 
FIG.  228. 


COMMON  GUINEA-FOWL  (Numida  meleagris). 

troduce  them  into  the  United  States.     The  guinea-fowl 
is  a  species  of  pheasant  that  has  been  domesticated  all 


BIRDS. 


283 


FIG.  229. 


over  the  civilized  globe.  Quail  of  various  species  are 
found  in  nearly  all  tem- 
perate regions.  In  some 
portions  of  the  United 
States  the  quail  is  erro- 
neously called  the  par- 
tridge, and  this  name  is 
also  applied  to  the  ruffed 
grouse,  a  large  gallina- 
ceous bird  found  in  the 
mountainous  regions  of 
the  United  States.  The 
prairie-hen  is  a  grouse. 
Partridges  are  not  found  COM;MON  QUA7L 
in  the  United  States  ex- 
cepting in  the  extreme  western  parts. 

PIG.  230. 


wt  rr"*»~~"^.  *-$*$&> 

a,  common  partridge  (Perdix  cinerea} ;  6,  red-legged  partridge  (Perdix  rufa). 

Columbae. — Pigeons  fly  heavily,  but  with  great  power, 
and  can  prolong  their  flight  for  a  considerable  time. 
They  usually  build  their  nests  in  trees  and  live  in  pairs, 


284 


A  COURSE  ON  ZOOLOGY. 


FIG.  231. 


although  sometimes  uniting  together  in  immense  flocks. 
Among  our  wild  pigeons  are  the  band-tailed,  the  red- 
billed,  the  white-crowned,  and  the  passenger.  The  com- 
mon wild  dove  of  the  United  States  is  the  mourning 
dove,  so  called  from  its  plaintive  cry.  The  species  of 
domestic  pigeon  are  exceedingly  numerous  ;  one  of  them, 
the  carrier  pigeon,  has  been  employed  for  ages  for  carry- 
ing messages  ;  when  taken  hundreds  of  miles  from  its 
home  it  is  able  to  find  its  way  through  the  air,  and 
quickly  returns  to  its  nest. 

Raptores, — In  their  habits  the  raptores  correspond  to 
carnivorous  mammals.  Some  live  on  small  birds  and 
quadrupeds,  others  on  fish,  reptiles,  and  insects.  Their 
toes  are  armed  with  strong,  hooked  claws,  called  talons  ; 

the  beak  is  straight  at  the 
base,  but  curved  towards 
the  end,  and  terminates  in 
a  sharp  point.  The  wings 
generally  have  a  wide  spread, 
and  most  of  the  order  are 
rapid  in  flight.  The  nests 
or  eyries  are  placed  on  high 
trees  or  inaccessible  rocks. 

We  may  distinguish  in  the 
order  the  nocturnal  family 
of  owls  from  the  other  fam- 
ilies, which  are  diurnal.  The 
latter  have  the  eyes  in  the 

HEAD  AND  FOOT  OF  BRA"  MANACLE.    side8  °f  the   head  '   thev  % 

and  hunt  during  the  day- 
time. Among  them  are  the  vultures,  kites,  hawks,  buz- 
zards, eagles,  and  sparrow-hawks. 

The  eagles  inhabit  mountains  and  steep  cliffs.     There 


BIRDS. 


285 


are  a  large  number  of  species,  among  which  we  may 
mention  our  bald  eagle,  so  called  from  its  white-feathered 
head,  and  the  golden  eagle,  which  is  distributed  all  over 

FIG.  232. 


GOLDEN  EAGLE  (Aquila  chrysaetus),  ADULT  MALE.— From  E.  T.  Booth's 
"  Birds  of  the  British  Islands"  (Porter,  London,  1881). 

Europe  and  North  America,  and  attains  a  length  of 
nearly  three  feet.  The  osprey  is  variously  called  the  fish- 
hawk  and  the  fishing  eagle ;  it  feeds  entirely  on  fish. 
Falcons  and  kites  are  found  principally  in  Europe,  the 
former  feeding  on  even  large  birds,  while  the  kite  is  a 
scavenger,  though  he  sometimes  robs  the  barn-yard.  The 
true  buzzards  are  an  inferior  sort  of  eagles  ;  one  of  them 
is  commonly  called  the  hen-hawk.  The  vultures  are  dis- 
tinguished from  the  preceding  species  by  their  naked 
head  and  neck,  and  the  relatively  inferior  strength  of 


286 


A    COURSE   ON    ZOOLOGY. 
FlG.  233. 


COMMON  KITE,  OR  GLEDE  (Milvus  ictinus). 
FIG.  234. 


CONDOR. 


BIRDS. 


287 


FIG.  235. 


the  talons.  They  feed  on  dead  animals,  and  act  as 
scavengers,  being  the  hyenas  of  the  class  of  birds.  The 
true  vultures  are  found  only  in  Europe,  there  being  a 
brown  species  and  a  yellow  one.  The  turkey  buzzard, 
more  properly  called  turkey  vulture,  is  the  most  common 
American  vulture.  The  condor  is  an  enormous  species 
of  vulture,  living  among  the  highest  Alps ;  its  wings 
have  a  spread  of  four  yards,  and  of  all  birds  it  is  the 
most  powerful  in  flight. 

The  owls  are  nocturnal  birds,  of  which  there  are  many 
species,  all  having  strong  resemblance  between  them. 
The  eyes  are  very  large,  and 
placed  in  the  front  of  the 
head  ;  they  do  not  like  the 
light,  and  remain  hidden 
during  the  day,  beginning 
to  hunt  at  dusk.  They  are 
carnivorous,  living  on  in- 
sects, small  reptiles,  birds, 
and  little  mammals,  all  of 
which  they  swallow  whole. 
Generally  they  do  not  con- 
struct nests,  placing  their 
eggs  in  holes  in  trees  or 
rocks,  or  in  abandoned  nests 
of  other  birds.  These  birds 
are  very  useful  to  the  farmer, 
destroying  large  numbers  of 
injurious  creatures.  Among 

the  species  may  be  mentioned  the  barn-owl,  screech- 
owl,  great  snowy  owl,  and  burrowing  owl, — the  latter 
being  the  species  that  shares  the  burrows  of  the  prairie- 
dog. 


BARN-OWL  (Strix flammed). 


288 


A   COURSE   ON   ZOOLOGY. 
FIQ.  236. 


Heads  of  a,  short-eared  owl ;  6,  long-eared  owl ;  and  c,  snowy  owl. 

Psittaci,— The  parrots,  paroquets,  and  cockatoos  are 
very  numerous.  They  have  thick,  short  bills,  and  large, 
fleshy  tongues.  They  do  not  fly  well,  but  climb  with 
great  ease,  using  for  this  purpose  both  the  beak  and  the 
feet.  They  carry  their  food  to  the  mouth  with  one  foot, 
standing  on  the  other.  They  live  on  nuts  and  seeds, 
which  they  are  able  to  extract 
FIG.  237.  from  the  shell,  however  hard 

that  may  be. 

The  cockatoos  are  found  in 
Australia  and  the  Indian  Archi- 
pelago, the  largest  species  being 
two  feet  in  length.  They  are 
white,  with  yellow  crests,  but 
there  is  a  black  species.  Par- 
rots are  found  in  nearly  all 
tropical  countries ;  a  large 
species  occurs  in  Mexico ;  and 
paroquets,  which  are  smaller, 
GRAY  PARROT.  are  found  as  far  north  as  the 

Carolinas. 

Coccyges, — We  need  mention  but  two  members  of 
this  order,  the  cuckoos  and  the  kingfishers.  The  former 
live  in  the  fields,  and  are  well  known  for  their  habit 
of  placing  their  eggs  in  the  nests  of  other  insectivorous 


BIRDS. 


289 


birds  which  are  smaller  than  themselves,  and  the  young 
cuckoo,  when  hatched,  manages  to  get  the  greater  part 
of  the  food,  and  frequently  pushes  the  rightful  heirs  of 
the  nest  over  its  borders.  The  belted  kingfisher  is  the 
common  species  in  the  North.  It  has  a  most  curious 
aspect,  the  head  appearing  as  large  as  the  body.  It 
makes  its  nest  at  the  extremity  of  a  horizontal  burrow 
in  the  earthy  bank  of  a  stream  or  lake. 

Fia.  238. 


KINGFISHER  (Alcedo  ispida). 

Pici.— Woodpeckers  are  of  all  sizes,  from  nineteen 
inches  in  length  down.  They  are  expert  climbers,  sink- 
ing their  strong,  hooked  claws  into  the  bark  of  trees 
and  supporting  themselves  by  the  aid  of  their  stiff  and 
inflexible  tail-feathers;  they  are  thus  able  to  climb  per- 
pendicular surfaces  with  great  ease.  The  beak  is  straight 
and  chisel-edged,  and  cuts  through  the  bark,  while  the 
very  long  tongue,  covered  with  a  sticky  saliva,  pene- 
trates the  hole,  seeking  the  larvae  of  insects.  Their  nests 
are  in  the  trunks  of  trees,  and  they  are  found  all  over  the 
N  t  26 


290  A   COURSE   ON   ZOOLOGY. 

world.     Some  are  very  plain  in  color ;  others  are  crested 
FIG.  239. 


THE  NIGHT-JAR  (Caprimulgus  europseus). 

or  marked  with  brilliant  red.     The  common  flicker  is 
an  insectivorous  bird  closely  allied  to  the  woodpecker. 


BIRDS. 


291 


Macrochires. — The  goatsuckers,  so  called  because  it 
was  formerly  imagined  that  they  suck  the  milk  of 
herds,  and  the  closely-allied  whippoorwill  are  birds  with 
sober-mottled  plumage.  The  nests  are  made  among  dead 
leaves  on  the  ground.  The  night-hawk,  which  is  not  a 

FIG.  241. 


o,  sword-bill  humming-bird  (Docimastes  ensifer);  b,  white-booted  racket-tail 
(Steganurus  Underwoodi) ;  c,  cf,  male  and  female  tufted  coquette  (Lophornis 
ornata). 

hawk  at  all,  is  of  this  order.  The  humming-birds,  exceed- 
ingly small,  of  which  there  are  many  species,  are  often 
very  beautiful,  the  minute  feathers  appearing  as  bril- 
liant scales,  having  lustrous  metallic  reflections.  They 
have  long  beaks  and  very  long  tongues,  which  they 
-thrust  into  flowers  for  the  purpose  of  feeding  on  small 
insects,  and  probably,  also,  on  the  nectar. 


292 


A   COURSE   ON    ZOOLOGY. 


CHAPTER  XXX. 
Birds  (continued) — Passeres. 

THE  order  passeres  includes  a  number  of  families,  and 
the  species  are  exceedingly  numerous,  usually  compara- 
tively small  in  size,  but  having  few  common  character- 
istics. They  all  have  the  toes  adapted  for  perching. 

The  fly-catchers,  of  which  the  kingbird  or  bee  martin 
is  a  type,  have  short,  strong  bills,  and  destroy  millions 
of  insects.  They  have  no  song,  the  cry  being  a  sort  of 
chirp. 

The  mocking-bird  of  America  and  the  nightingale  of 

FIG.  242. 


MOCKING-BIRD  (Mimus  polyglottus) . 

Europe  are  very  plain  in  plumage,  but  are  remarkable 
songsters,  and  make  the  groves  melodious  at  night. 
These  and  the  bluebird  belong  to  the  thrush  family,  as 
does  the  robin  redbreast.  Both  these  birds  are  very 


BIRDS. 


293 


familiar,  and  make  their  nests  very  near  country  houses. 
FIG.  243. 


BLUEBIRD  (Sylvia  sialis), 
FIG.  244. 


COMMON  CREEPER  (Certhiafamiliaris). 

The  creepers  are  common  all  over  the  northern  hemi- 
sphere ;  their  feet  are  adapted  to  tree-climbing,  and  in 

25* 


294 


A    COURSE    ON    ZOOLOGY. 


this  they  are  aided  by  the  stiff  feathers  of  the  tail.     The 
FIG.  245. 


<  ^  -        ' 

LAEK  (Alauda  arvensis). 
FIG.  246. 


RAVEN  (Corvus  corax). 


wrens,  chickadees,  tits,  wagtails,  and  sparrows  are  pas 
seres,  and,  indeed,  the  order  is  named  from  the  latter 


BIRDS. 


295 


species.     There  are  several  species  of  larks,  those  found 
FIG.  247. 


RAVEN  AND  BOOK  HEADS. 
FIG.  248. 


COMMON  MAGPIE  (Pica  rustica). 


in  America  being  the  horned  larks,  having  little  horn- 
like tufts  of  black  feathers  on  each  side  of  the  head. 


296 


A   COURSE   ON    ZOOLOGY. 


The  skylark  is  a  European  bird.      The  crows,  ravens, 
jays,  and  magpies  belong  to  the  crow  family.     There  is 

FIG.  249. 


FIG.  250. 


BLACKBIRD. 

but  little  difference  between  the  crow,  the  raven,  and  the 
rook,  these  birds  being  the  largest  of  the  passeres,  and 

the  whole  family  being 
omnivorous.  The  rook 
has  a  bare  space  about 
the  margins  of  the  bill. 
In  some  countries  the 
crow  acts  as  a  scavenger, 
street-cleaning  being  left 
to  it  entirely.  It  likes 
to  follow  the  sower  in 
the  field  and  eats  large 
quantities  of  grain,  but 
at  the  same  time  it  de- 
stroys innumerable  in- 


magpie  can  be  easily 
tamed,  but  are  very  mischievous.  The  crows  and 
ravens  are  black  ;  the  magpies  have  rich  metallic  re- 


BIRDS. 

FIG.  251. 


297 


BOBOLINK. 


FIG.  252. 


BULLFINCH. 


298 


A    COURSE    ON  ZOOLOGY. 


flections,  purple,  green,  and  brown  ;  the  jays  are  of  many 
colors,  the  blue  jay  being  one  of  the  most  common. 

The  blackbird  family  includes  the  orioles,  one  of  the 
most  beautiful  of  which  is  the  Baltimore  oriole,  rich 
orange  in  color.  Some  of  the  blackbirds  have  beautiful  red 
wings.  The  meadow-larks  are  of  this  family,  as  is  also  the 
bobolink,  reed-bird,  or  rice-bird,  as  it  is  variously  called. 

The  wrens,  chickadees,  tits,  wagtails,  sparrows,  and 


FIG.  253. 


GOLDFINCH  (Carduelis  elegans). 

finches  are  passeres,  but  of  different  families.  They  are 
of  various  colors,  usually  sober,  but  some  of  the  finches 
are  brightly  tinted.  The  swallows  and  martins  prefer 
to  build  their  nests  under  the  eaves  of  houses,  in  chim- 
neys, or  in  the  crevices  of  walls.  All  the  warblers, 
honey-creepers,  cat-birds,  tanagers,  and  buntings  are 
passeres,  and  the  order  includes  about  half  the  known 
birds.  Most  of  the  species  are  migratory,  preferring 
temperate  climates,  and  flying  northward  in  the  spring, 
again  to  return  south  on  the  approach  of  winter. 


TORTOISES.  299 

CHAPTER  XXXI. 
Reptiles  and  Batrachians. 

THE  reptiles  are  classified  in  five  orders,  as  follows : 

1.  Chelonia :  having  limbs  and  bodies  usually  covered 
with  horny  scales  ;  the  jaws  terminate  in  a  horny  beak  : 
tortoises  and  turtles. 

2.  Rhyncocephalia  :    only    one    representative,    New 
Zealand  sphenodon. 

3.  Lacertilia :  bodies  having  limbs  and  covered  with 
scales  ;  teeth  :  lizards,  chameleons,  etc. 

4.  Ophidia :  no  limbs,  scales,  teeth  :  snakes. 

5.  Crocodilia :  much  like  the  lacertilia,  but  the  heart 
has  four  cavities  as  in  the  birds :  crocodiles   and   alli- 
gators. 

CHELONIA. 

Tortoises  have  a  horny  beak,  analogous  to  that  of 
birds.  The  body  is  covered  by  a  carapace,  which  forms 
a  sort  of  double  shield  protecting  the  entire  trunk,  and 
within  which  the  head,  tail,  and  limbs  can  be  drawn 
when  necessary.  The  up- 
per shield  is  formed  by  the 
union  of  the  ribs  and  dorsal 
vertebrae,  and  is  known  as 
the  carapace.  It  is  joined 
to  the  lower  shield,  called 

plastron,  by  bands   Of  bony    ToRTOisE.-Its  body  is  enveloped  in 
rp/  a  solid  box,  called  a  shell. 

pieces.     Ine  motor  muscles 

of  the  limbs  and  shoulder  and  the  pelvis  are  enclosed 

in  the  carapace. 

The  union  of  the  ribs  renders  the  mechanism  of  res- 


300  A   COURSE   ON   ZOOLOGY. 

\ 

piration  of  the  tortoise  very  different  from  that  of  ani- 
mals whose  ribs  are  mobile,  and  tortoises  take  in  air  by 
an  act  of  swallowing.  This  air  enters  the  mouth  by  the 
nostrils,  and  the  tongue  acts  as  a  valve,  which  forces  it 
into  the  pharynx  and  towards  the  lungs. 

According  to  the  form  and  habits,  the  chelonia  may 
be  arranged  in  three  groups :  sea  tortoises,  fresh-water 
tortoises,  and  land  tortoises,  The  aquatic  species  are 
generally  called  turtles. 

The  land  tortoises  have  large  feet,  terminating  in  a  sort 
of  stump,  and  usually  a  very  arched  carapace,  which  com- 
pletely protects  all  parts  of  the  animal.  The  largest 
American  species  is  the  gopher  tortoise,  found  in  the 
Southern  States  ;  its  length  is  about  fourteen  inches,  its 
shell  very  convex,  brownish  yellow,  tinged  with  dark 
brown.  The  box  tortoise  is  our  common  land  tortoise, 
and  grows. to  a  length  of  about  six  inches.  The  Greek 
tortoise,  found  on  the  borders  of  the  Mediterranean,  is 
much  esteemed  as  food.  All  the  land  tortoises  bury 
themselves  in  the  soil  during  the  winter,  sleeping  there 
until  spring. 

The  fresh-water  turtles  have  palmate  feet  and  a  flat- 
tened carapace,  sometimes  without  plates  and  covered 
with  a  soft  skin.  One  of  the  smaller  species  is. the  mud- 
turtle,  about  six  inches  long ;  it  is  found  all  over  North 
America ;  the  skin  of  its  limbs  is  orange-colored,  and  it 
is  edible.  Larger  species  are  the  alligator  terrapin, 
found  in  Southern  waters,  and  the  snapping-turtle,  well 
known  for  its  strength  and  ferocity. 

The  tide-water  turtles  are  usually  called  terrapin,  and 
are  much  sought  for  their  flesh  ;  among  them  the  dia- 
mond-back, which  attains  a  length  of  six  or  seven  inches, 
is  most  prized. 


LIZARDS.  301 

The  sea-turtles  have  limbs  terminating  in  a  sort  of  fins, 
and  the  carapace  is  not  large  enough  to  receive  the  head 
and  limbs.  They  are  found  in  warm  seas  and  grow  to  a 
great  size,  specimens  having  been  taken  that  weighed 
seventeen  hundred  pounds.  The  flesh  of  the  green 
turtle  is  highly  esteemed.  The  hawksbill  or  caret  fur- 
nishes tortoise-shell,  each  individual  having  thirteen 
large  plates  in  the  centre  of  the  carapace,  and  twenty- 
five  smaller  ones  on  the  borders. 

RHYNCOCEPHALIA — LACERTILIA. 

The  order  of  rhyncocephalia  is  represented  by  but  one 
living  species,  the  New  Zealand  lizard  or  sphenodon, 
remarkable  in  having  a  third  eye. 

The  general  characteristics  of  the  lizards  have  been 
given  in  Chapter  X.,  and  we  need  not  reconsider  them. 
The  species  of  lacertilia  are  very  numerous ;  some  very 
small,  others  exceedingly  large.  The  largest  is  the  mon- 
itor of  the  Nile,  an  aquatic  lizard  that  grows  to  a  length 
of  six  or  seven  feet.  Then  come  the  iguanas,  a  large 
family,  the  species  being  variously  and  brilliantly  colored ; 
they  occur  in  South  America  and  the  West  Indies,  and 
attain  a  length  of  from  three  to  five  feet.  The  geckos  are 
dull  in  color,  inhabitants  of  Southern  Europe,  India,  and 
Egypt,  attaining  a  length  of  more  than  two  feet.  The 
poisonous  Gila  monster,  found  in  the  sandy  deserts  of  New 
Mexico,  Arizona,  and  Texas,  has  brilliant  black  and 
orange  scales  ;  it  is  more  than  a  foot  long,  and  is  the  only 
venomous  lizard,  excepting  the  closely-allied  Mexican 
lizard.  The  horned  toads  of  the  Southern  United  States 
are  lizards,  as  are  also  the  glass-snake  of  the  United 
States  and  the  slow-worm  of  Europe. 

The  chameleons  have  the  power  of  changing  color 
26 


302 


A 


A  COURSE  ON  ZOOLOGY. 
FIG.  255. 


COMMON  IGUANA  (Iguana  tuber culatus). 
FIG.  256. 


FRINGED  GECKO  (Ptychozoon  homalocephalum). 

according  to  their  surroundings ;  this  faculty  appears  to 


LIZARDS. 


303 


be  owing  to  the  fact  that  the  skin  contains  two  differ- 
ent layers  of  pigment,  one  yellowish  gray,  the  other 


FIG.  257. 


GILA  MONSTER  (Heloderma  suspectum). 
FIG.  258. 


CHAMELEON. 


dark  red ;  the  tint  of  the  skin  will  then  be  determined 
by  the  color  which  predominates  according  to  the  im- 
pressions of  the  animal.  The  eyes  of  the  chameleon 


304 


A    COURSE   ON    ZOOLOGY. 


are  very  prominent  and  very  mobile,  and  they  can  be 
turned  in  opposite  directions  j  the  long  tongue  can  be 
thrust  far  out  to  seize  insects,  and  the  round  and  pre- 
hensile tail  can  grasp  tree-branches,  etc.  The  digits,  like 
those  of  parrots,  are  arranged  in  two  opposing  pairs  on 
each  limb.  The  lungs  are  large,  and  when  fully  inflated 
nearly  double  the  bulk  of  the  body.  The  common 
chameleon  rarely  exceeds  fifteen  inches  in  length. 


FIG.  259 


OPHIDIA. 

Serpents  have  no  limbs;  their  extremely  elongated 
bodies  are  moved  by  a  series  of  lateral  flexures.  The 
vertebrae  and  the  ribs  alone  constitute  almost  the  entire 
skeleton.  The  water-adder  has  more  than  three  hun- 
dred vertebrae ;  the  viper  about  two  hundred.  The  eyes 
of  serpents  have  a  fixed  appearance,  caused  by  the 
existence  of  but  one  eyelid ;  this  eyelid  is  fixed  and 
transparent,  and  covers  the  eyeball  as  would  a  watch- 
crystal.  The  tongue  is 
long,  slender,  and  ordi- 
narily bifurcated ;  it  is 
frequently  thrust  out, 
and  this  has  given  rise 
to  the  erroneous  notion 
that  it  could  be  used  as 
a  sting. 

The  mouth  is  always 
armed  with  teeth,  but 
these  organs  are  of  lit- 
tle service  excepting  to 
retain  the  prey,  which 
is  swallowed  entire,  after  a  process  of  softening  and 
crushing  that  sometimes  lasts  several  days.  The  ex- 


POISON  APPARATUS  OK  THE  RATTLESNAKE.— 

g,  poison-gland,  having  a  duct  opening 
into  a  canal  in  the  fang ;  m,  muscles  that 
compress  the  gland  and  close  the  jaws ; 
d,  poison-fangs ;  s,  salivary  glands  ;  /, 
nostril. 


SERPENTS.  305 

treme  extensibility  of  the  jaws,  which  are  readily  dis- 
located, allows  serpents  to  swallow  animals  much  larger 
than  themselves.  Many  of  these  reptiles  inject  into  the 
wounds  made  by  their  teeth  an  exceedingly  poisonous 
liquid  ;  the  venom  is  secreted  by  glands  located  behind  the 
eye,  and  communicating  by  a  duct  with  the  fangs.  These 
teeth  are  rooted  in  the  upper  jaw,  and  have  either  a 
tubular  canal  or  a  simple  groove  by  which  the  venom 
descends  when  the  poison-bag  is  compressed  by  muscu- 
lar contraction  as  the  serpent  strikes ;  serpents  do  not 
bite.  It  has  been  recently  found  that  venomous  serpents 
suifer  no  ill  effects  from  self-inflicted  wounds,  and  that 
the  poison  is  not  dangerous  to  other  individuals  of  the 
same  species,  nor  to  other  ophidia  generally. 

We  may  classify  serpents  as  venomous  and  non-ven- 
omous. 

The  largest  of  the  non-venomous  serpents  are  the 
pythons  of  Asia  and  Africa,  and  the  anacondas  and  boas 
of  South  America.  The  first  two  may  attain  a  length 
of  twenty  or  thirty  feet,  and  they  have  great  crushing 
power,  being  able  to  seize  even  large  animals,  and  strangle 
and  crush  them  in  their  folds.  The  largest  animals  that 
they  can  swallow  do  not,  however,  exceed  the  size  of  a 
small  dog. 

Among  the  non-venomous  snakes  of  the  United  States, 
the  more  common  are  the  black  snake,  the  pine-snake, 
which  is  mottled  white  and  black  or  brown,  and  is  some- 
times more  than  six  feet  long,  the  scarlet  snake  of  the 
South,  the  garter-snakes,  the  small  green  snakes,  the 
common  water-snakes  of  a  dark  greenish  color,  and  the 
banded  and  striped  water-snakes.  These  snakes  are 
more  useful  than  noxious  to  man,  for  they  destroy  for 
their  food  large  numbers  of  snails  and  insects,  field  rats 
u  26* 


306          «  A   COURSE   ON    ZOOLOGY. 

\  -  ',-    . 

and  mice,  etc.,  as  well  as  frogs  and  toads.     Their  bites 
are  not  at  all  dangerous. 

FIG.  260. 


PYTHON  (Python  sebx/  swallowing  a  bird. 
FIG.  261. 


RATTLESNAKE  (Crotalus  horridus)  in  act  of  striking. 

The  most  dreaded  of  our  venomous  serpents  are  the 
species  of  crotalus  or  rattlesnake.  In  these  the  end  of 
the  tail  carries  a  curious  apparatus,  consisting  of  a  num- 


CROCODILES.  307 

her  of  articulated  horny  rings,  and  terminating  in  a  sort 
of  button.  By  agitating  this  the  rattlesnake  produces  a 
noise  much  like  that  of  the  locust,  this  noise  being  usually 
made  when  the  snake  is  excited.  The  number  of  rings 
is  increased  with  successive  sloughings  or  castings  of  the 
skin,  but  does  not  indicate  the  age  of  the  animal.  There 
are  three  other  poisonous  serpents  in  the  United  States  : 
the  water  moccason  and  the  small  harlequin  snake  of  the 
South,  and  the  copperhead,  so  called  from  its  coppery 
color,  of  the  North. 

Among  the  poisonous  snakes  of  other  countries  the 
better  known  are  the  cobra  of  India,  whose  bite  causes 
large  numbers  of  deaths  annually,  the  puff  adder  of 
Southern  Africa,  and  the  fer  de  lance  of  Martinique. 
The  stings  of  venomous  serpents  rapidly  paralyze  the 
nerve-centres,  and  depress  the  circulatory  and  respira- 
tory functions ;  at  the  same  time  there  is  great  local  and 
general  swelling  of  the  affected  part  and  its  vicinity. 

CROCODILIA. 

Crocodiles  grow  to  a  large  size.  Their  bodies  are  pro- 
tected by  a  hard  scaly  hide,  which  is  almost  impenetrable 
by  bullets.  Their  diet  is  carnivorous,  their  life  aquatic  ; 
they  cannot  walk  well  on  shore,  their  bodies  being  too 
heavy  for  the  legs,  but  they  swim  very  rapidly.  The 
larger  species  are  dangerous  to  man,  the  crocodile  of 
the  Nile  being  said  to  attain  a  length  of  thirty  feet, 
although  those  seen  are  not  often  more  than  half  that 
long.  The  ancient  Egyptians  worshipped  them. 

The  alligators  have  shorter  and  broader  heads  than 
the  crocodiles,  and  are  not  so  large,  the  greatest  length 
being  about  twenty  feet.  They  are  found  in  the  waters 
of  South  America,  Mexico,  and  the  Southern  United 


308 


A    COURSE    ON    ZOOLOGY. 


States.      They  rarely  attack  man,  especially  when  on 
land. 

FIG.  262. 


CROCODILE. 


The  gavials  are  of  the  crocodile  order,  but  differ  from 
the  crocodiles  and  the  alligators  in  having  a  long,  slender 


FIG.  263. 


PIKE-HEADED  ALLIGATOR  (Alligator  Indus). 

snout.  They  occur  in  India,  Java,  and  Borneo,  and  the 
most  common  species  is  that  of  the  Ganges,  whose  length 
is  about  twenty-four  feet. 


BATRACHIANS. 


BATRACHIANS. 


309 


The  general  characters  of  the  batrachians  have  been 
considered  in  the  chapter  on  the  frog. 

They  are  classified  as  (1)  anura,  those  having  no  tails, 
like  the  frogs  and  toads ;  (2)  urodela,  those  having  tails, 
such  as  the  newt  and  salamander;  (3)  caecilia,  which 
have  no  limbs. 

We  need  not  repeat  what  has  been  said  of  frogs,  but 
may  add  that  some  toads  are  the  most  repulsive  in 
aspect  of  the  batrachians.  Their  skin  secretes  an  acrid 
liquid,  which  exudes  when  the  creature  is  irritated. 
Tales  are  often  told  of  toads  discovered  in  rocks  or 
trunks  of  trees,  where  they  must  have  remained  many 
years  imprisoned ;  exact  experiments  have  shown  that 
batrachians  of  this  kind  may  live  rather  more  than  a 
year  in  an  envelope  permeable  by  air,  such  as  plaster, 
or  porous  calcareous  formations,  but  that  when  inclosed 
in  an  impermeable  envelope,  like  metal  or  clay,  they 
perish  in  about  a  month. 

FIG.  264. 


GREAT  WATER  NEWT  ( Triton  cristatus). 

The  newts,  or  tritons,  and  salamanders,  retain  through- 
out life  the  tail  which  is  present  in  the  tadpole  stage  of 
the  frog.  The  salamanders  are  terrestrial,  being  found 
in  moist  places ;  the  newts  are  aquatic,  being  able  to 
crawl  only  slowly  on  land.  All  are  usually  small,  inof- 
fensive creatures,  but  the  giant  salamander  of  Japan 


310 


A   COURSE   ON    ZOOLOGY. 


attains  a  length  of  three  feet.     Like  the  lizards,  the  uro- 
dela  have  the  singular  property  of  replacing  lost  parts. 


FIG.  265. 


LARVAE  OF  TEITON  CRISTATUS.— A,  condition  before  leaving  the  egg ;  B,  tad- 
pole shortly  after  it  is  hatched ;  C,  at  about  the  twenty -second  day ;  D,  at 
about  the  forty-second  day. 


CHAPTER  XXXII. 
Pishes. 

THE  general  characters  of  fish  as  a  class  have  been 
studied  in  Chapter  XI.,  the  example  being  the  carp. 

The  classification  of  fish  is  based  first  on  the  nature  of 
the  skeleton  ;  those  having  an  osseous  skeleton  are  called 
teleostei,  and  are  by  far  the  more  numerous ;  those  in 
which  the  skeleton  is  cartilaginous  constitute  the  sub- 
class chondropterygii.  The  first  subclass  is  divided  into 
orders  according  to  the  condition  of  the  premaxillary 


FISHES. 


311 


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a 

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7 

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e    5 


Si 

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&'&•»•£  °      a  S  t*  Q -41 

flfflliflis 

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eo     ^^^    gga| 

a  „       S  SS  ff  H 


Lower  ph 
bones  s 


der 


312  A   COURSE   ON   ZOOLOGY. 

bones,  the  presence  or  absence  of  spinous  rays  on  the 
dorsal  fins,  the  position  of  the  ventral  fins,  and  the 
existence  or  absence  of  a  duct  connected  with  the 
swimming-bladder.  This  classification  is  shown  in  the 
table  on  page  311. 

BONY   FISHES    (TELEOSTEl). 

Acanthopterygii  (spine-finned).  —  The  fresh-water 
perches  are  of  medium  size,  eight  to  twelve  inches  long, 
very  carnivorous,  and  very  destructive  to  other  fish. 
The  flesh  is  white  or  pale-yellow,  and  is  excellent  and 
wholesome  food.  The  black  bass  and  striped  bass,  or 

FIG.  266. 


PEECH  (Perca  fluviatilis). 

rock-fish,  are  game  fishes;  they  prefer  cold  and  rapid 
waters ;  the  spines  in  the  dorsal  fin  are  very  sharp,  and 
the  head  of  the  first  is  large.  The  mullet  and  red- 
mullet  have  delicate  flesh ;  they  feed  on  the  organic 
matter  found  in  muddy  bottoms, — the  mullet  being  a 
fresh-water  and  the  red-mullet  a  marine  fish. 

The  mackerel  is  ordinarily  between  twelve  and  six- 
teen inches  long,  and  is  found  in  almost  all  temperate 
and  tropical  seas,  excepting  on  the  American  coasts  of 
the  South  Atlantic.  They  move  in  shoals,  approaching 


BONY    FISHES. 


313 


the  shores  for  feeding  or  spawning.     The  mackerel  is 
highly  esteemed  as  food,  but  its  flesh  spoils  rapidly. 


FIG.  267. 


SUKMULLET. 

The  Spanish  mackerel,  or  tunny  fish,  has  bright-yellow 
spots  on  the  sides,  and  grows  much  larger  than  the 
common  mackerel.  It  is  an  excellent  food-fish,  and  is 
generally  preserved  in  oil. 

FIG.  268. 


COMMON  MACKEREL  (Scomber  scomber). 

The  blue-fish  is  one  of  the  finest  fishes  of  the  Atlantic 
coasts  of  the  United  States ;  it  is  very  rapacious,  and  it 
furnishes  excellent  sport.  Some  have  been  caught  five 
feet  long,  but  those  usually  taken  average  about  two  feet 
in  length. 

o  27 


314 


A  COURSE  ON  ZOOLOGY. 


The  flying-fish  of  the  Gulf  of  Mexico  and  the  tropical 
Atlantic  is  the  flying-gurnard ;  its  pectoral  fins  are  so 


FIG.  269. 


SAPPHIRINE  GURNARD  (Trigla  hirundo, 
FIG.  270. 


SWORD-FISH. 


largely  developed  that  the  fish  can  leave  the  water,  con- 
tinuing its  course  in  the  air  for  a  distance  as  great  as 
five  hundred  yards. 
The  sword-fish  is  remarkable  for  the  extensive  bony 


BONY    FISHES. 


315 


prolongation  of  its  upper  jaw,  called  its  sword,  which  it 
uses  as  a  weapon,  and  with  which  it  can  even  pierce  the 
planking  of  ships.  It  has  no  teeth. 

Acanthopterygii  pharyngognathi. — The  species  of 
wrass,  among  which  is  the  parrot-fish,  belong  to  this 
order.  They  have  strong,  bony  jaws,  the  teeth  being 
firmly  united  together. 

FIG.  271. 


CODFISH. 

Anacanthini. — This  order  has  no  spinous  rays  in  the 
dorsal  or  ventral  fins,  and  if  an  air-bladder  be  present 
it  has  no  duct.  The 

family   of  codfishes  FIG.  272. 

form  the  most  im- 
portant members, 
constituting  the 
means  of  life  and 
the  food  of  whole 
cities  and  tribes  on 
the  North  Atlantic 
coasts.  Cod-liver  oil 

is  made  from  the  livers  of  these  fish.  The  haddock  and 
the  hake  belong  to  this  family.  The  sand-eel,  much 
used  as  bait  in  sea-fishing,  belongs  to  another  family 
of  the  same  order. 


SAND-EEL  OR  SAND-LANCE  (Ammodytes  lancea). 


316 


A    COURSE   ON    ZOOLOGY. 


The  flat-fishes  constitute  an  interesting  family,  called 
pleuronectidae ;  among  all  the  vertebrates  they  are  the 
only  ones  that  are  not  symmetrical.  They  have  no 
swimming-bladder,  and,  on  account  of  the  arrangement 
of  their  fins,  they  can  rest  and  move  only  on  one  side  of 
the  body,  which  is  flat.  Tho  two  eyes  are  on  one  side, 
and  this  is  always  the  darkest,  the  other  being  white  or 
very  light  in  color.  The  two  sides  of  the  mouth  are 
unequal;  swimming  is  accomplished  by  an  undulating 
movement  of  the  whole  body,  and  the  darker  side  is  al- 
ways uppermost.  They  prefer  sandy  bottoms,  and  are 
not  found  at  great  depths ;  some  live  only  in  the  sea, 
others  frequent  fresh  water ;  they  are  all  carnivorous. 

FIG.  273. 


HALIBUT  (Hippoglossus  vulgaris). 

Among  the  important  species  are  the  halibut,  the  sole, 
not  found  in  American  waters,  the  turbot,  the  floun- 
der, and  the  plaice. 

Physostomi. — In  this  order  all  the  fin  rays  are  artic- 
ulated, excepting  the  first  ray  of  the  dorsal  and  pectoral 
fins,  which  is  sometimes  ossified.  The  ventral  fins  have 


BONY    PISHES.  317 

no  spines,  and  are  abdominal  if  present ;  excepting  in 
one  family,  the  air-bladder  has  a  duct. 

The  order  includes  the  common  catfish,  frequently 
called  bull-head,  the  minnow,  chub,  sucker,  carp,  gold- 
fish, trout,  salmon,  pike,  muskallunge,  smelt,  herring, 
shad,  sardine,  anchovy,  menhaden,  electric  eel,  common 
eel,  and  conger  eel. 

The  catfish  sometimes  attains  a  great  length.  It  has, 
as  have  several  others  of  this  order,  barbels  on  the  upper 
and  lower  jaws,  and  it  is  well  armed  with  sharp  rays  on 
the  dorsal  and  pectoral  fins,  which  require  great  care  in 
handling.  The  minnow  and  chub  are  common  in  nearly 
all  our  streams  and 
lakes.  Carp  are  beau-  PIG.  274. 

tiful  fish  in  the  water, 
their  scales  reflecting 
a  silvery  light ;  some 
species  have  barbels, 
some  have  none ;  their 
ordinary  length  is  one 

or  two  feet,  but  they  have  been  caught  as  long  as  five. 
The  sucker  is  a  sort  of  carp,  and  so  is  the  gold-fish. 

Of  all  fresh -water  fish  none  are  more  highly  es- 
teemed for  the  table,  for  their  beauty,  and  for  the  sport 
of  taking  them  than  the  trout  and  the  salmon,  but  the 
salmon  is  not  really  a  fresh-water  fish ;  it  leaves  the 
deep  ocean  in  spring  and  ascends  rivers  almost  to  their 
sources  for  the  purpose  of  spawning ;  during  this  season 
it  is  fished  for.  The  flesh  of  both  the  salmon  and  trout 
is  reddish  and  very  palatable.  Trout  seek  the  coldest 
and  most  rapid  waters. 

The  pike  and  pickerel  have  beak-shaped  noses,  and  are 
exceedingly  voracious,  devouring  nearly  all  other  fish 

27* 


318  A   COURSE   ON    ZOOLOGY. 

that  are  found  in  the  same  waters.     The  muskallunge 
of  the  St.  Lawrence  and  of  the  large  northern  lakes  is 
a   fish  of  the  same  family ;   it 
FIG.  275.  attains  a  very  large  size. 

Herring  have  been  supposed 
to  migrate  annually,  and  their 
appearance  in  certain  parts  is 
so  uniform  that  the  direction  of 
their  voyages  was  considered 
TEETH  OP  THE  PIKE  (camiv-  known ;  starting  from  the  North- 
ern Atlantic,  they  appear  to 

form  two  immense  shoals,  one  of  which  takes  a  westerly 
direction  towards  America,  while  the  other  descends 
towards  the  European  seas  and  breaks  up  into  three 
divisions ;  one  of  these  proceeds  towards  the  British 
Isles,  another  towards  Norway  and  the  Baltic,  and 
the  third  enters  the  North  Sea,  crosses  the  English 
Channel,  and  advances  as  far  as  the  mouth  of  the 
Loire.  Eecent  investigations,  however,  seem  to  show 
that  the  migration  is  only  apparent,  and  that  during  the 
greater  part  of  the  year  the  herring  live  at  considerable 
depths  in  the  ocean  where  the  nets  cannot  reach  them ; 
at  the  beginning  of  the  spawning  season  they  ascend 
all  at  once,  and  appear  from  place  to  place  on  the  coast ; 
thus,  there  is  no  travelling  from  north  to  south,  but  a 
change  from  deep  to  superficial  water.  The  herrings 
place  their  eggs  in  a  froth  which  they  blow  up  on  the 
surface  of  the  water. 

Sardines  are  taken  principally  in  the  Mediterranean 
and  on  the  coasts  of  Brittany  ;  more  than  six  hundred 
million  are  caught  every  year,  and  as  soon  as  caught 
they  are  salted,  for  they  spoil  very  quickly.  Some  are 
sent  to  market  in  salt,  the  rest  are  preserved  in  oil. 


BONY   FISHES. 


319 


Anchovies,  taken  principally  in  the  Mediterranean,  are 
prepared  in  the  same  manner. 

Vast  shoals  of  shad  run  up  our  rivers  in  the  early 
spring  for  the  purpose  of  spawning,  and  large  numbers 
are  taken  in  nets.  Only  at  this  season  is  their  flesh  a 
palatable  food.  The  menhaden  or  mossbunker  is  exceed- 
ingly numerous  on  our  Atlantic  coasts,  and  enormous 
numbers  are  taken  annually  for  the  manufacture  offish- 
oil,  the  refuse  of  the  oil-factories  being  used  in  the 
preparation  of  manures. 

FIG.  276. 


COMMON  EEL  (Anguilla  vulgaris). 

Ordinary  eels  live  alternately  in  fresh  and  in  salt 
waters,  but  they  readily  become  accustomed  to  a  perma- 
nent life  in  ponds  and  streams.  They  sometimes  leave 
the  water  for  a  time,  either  in  search  of  insects  on 
bushes  or  in  order  to  reach  a  neighboring  piece  of 
water,  and  in  the  latter  case  they  can  travel  quite  a  dis- 
tance. 


320 


A   COURSE   ON    ZOOLOGY. 


FIG.  277. ^       The  conger  eel  is  commonly 

called  the  sea-eel ;  it  attains 
a  length  of  from  three  to  six 
feet  and  is  sometimes  much 
longer.  The  gymnotus,  or  elec- 
tric eel,  has  the  general  form 
of  ordinary  eels.  It  is  about 
six  feet  long,  and  possesses  a 
powerful  electrical  apparatus, 
capable  of  communicating  a 
violent  shock  to  very  large 
animals.  It  is  found  in  the 
rivers  and  marshes  of  South 
America. 

Lophobranchii  and  plectognathi. — These  two  orders  are 
interesting  to  us  chiefly  on  account  of  the  strange  forms 

FIG.  278. 


HIPPOCAMPUS  ANTIQUORUM. 


A,  globe-fish  (Diodon  maculatus) ;  B,  the  same  inflated. 


CARTILAGINOUS   FISHES.  321 

of  some  of  their  members.  Of  the  first  we  will  cite  only 
the  hippocampus  or  sea-horse,  sometimes  caught  in  our 
bays  and  rivers,  and  of  the  second,  the  globe-fish,  which 
has  a  curious  power  of  inflating  itself. 

CARTILAGINOUS   FISHES    (CHONDROPTERYGIl). 

We  may  subdivide  the  cartilaginous  fishes  into  sela- 
choids,  including  the  sharks,  sea-fish,  rays,  and  torpedos, 
and  ganoids,  composed  of  the  sturgeon  family.  The 
selachoids  have  no  air-bladder ;  the  ganoids  have  an  air- 
bladder  provided  with  a  duct. 

Selachoids. — Sharks  are  found  in  all  seas,  and  grow  to 
an  enormous  size ;  some  as  long  as  thirty  feet  having 

FIG.  279. 


WHITE  SHARK  (Carchariasvulgaris). 

been  taken,  and  these  are  small  compared  to  extinct 
species,  which  measured  seventy-five  feet  or  more  in 
length.  The  mouth  of  a  large  shark  is  sometimes  two 
yards  in  circumference,  and  its  borders  are  covered  with 
four  or  six  rows  of  teeth  as  sharp  and  cutting  as  the 
teeth  of  a  saw.  The  voracity  of  the  shark  is  proverbial  ; 
they  swallow  everything  they  come  across  floating  in 
the  water.  Ships  are  often  followed  by  schools  of  them. 


322 


A    COURSE    ON    ZOOLOGY. 


Dog-fish  belong  to  the  same  class  as  sharks  ;  they  grow 
as  long  as  three  feet,  and  the  flesh  of  some  species  is 
eaten.  The  skin  of  the  sea-dog  is  prepared  and  used  as 
"  rub-skin,"  for  polishing  wood  and  ivory.  The  muzzle 

FIG.  280. 


SAW-FISH. 

of  the  saw-fish  terminates  in  a  strong  bony  plate  armed 
on  the  edges  with  sharp,  pointed  teeth.  Rays  and 
skates  have  a  rhomboidal  body,  a  slender,  cylindrical 
tail,  the  eyes  and  gill-holes  in  the  upper  portion  of  the 
head,  the  mouth  below  and  armed  with  thin,  obtusely- 
pointed  teeth.  Some  of  the  skates  attain  a  large  size, 
measuring  more  than  six  feet  across.  They  are  edible, 
and  some  species  are  much  esteemed.  The  torpedo,  or 


CARTILAGINOUS    FISHES.  323 

electric  ray,  has  a  smooth,  naked,  almost  circular  body, 
and  a  long,  fleshy  tail ;  it  possesses  a  powerful  electric 
battery,  the  discharge  from  which  can  disable  a  strong 
man.  It  is  found  in  the  Atlantic  and  Indian  Oceans  and 
in  the  Mediterranean. 

FIG.  281. 


ELECTKIC  BAY. 


Ganoids, — The  sturgeon  lives  in  nearly  all  seas,  and  at 
certain  seasons  ascends  large  rivers,  where  it  is  taken  in 
nets.  It  has  no  teeth,  and  feeds  on  small  fish,  and  even 
larvae,  which  it  digs  out  of  the  mud  with  its  tough  nose. 


FIG.  282. 


STURGEON  (Acipenser  sturio). 


Its  body  is  protected  by  several  rows  of  osseous  bucklers, 
arranged  longitudinally  on  the  surface  of  the  skin.     It 


324  A   COURSE   ON   ZOOLOGY. 

grows  to  a  length  as  great  as  ten  feet.  The  flesh  is 
used  as  food,  caviare  is  prepared  from  the  eggs,  while 
the  interior  of  the  swimming-bladder  furnishes  isinglass. 

CYCLOSTOMATA. 

The  members  of  this  group  differ  from  the  true  fishes 
in  having  no  jaws,  no  paired  fins,  no  scales,  and  they 
possess  gill-pouches  that  act  like  lungs.  The  lamprey 

FIG.  283. 


LAMPKEV  (Petromyzon  marinus). 

and  the  hag-fish  are  examples  ;  the  first  a  marine,  the 
second  a  fresh-water  species.  They  have  round  mouths, 
in  which  the  tongue  works  like  a  piston,  so  that  they 
can  attach  themselves  to  the  skin  of  fishes  and  suck  not 
only  blood  but  flesh. 


INSECTS.  325 

CHAPTER  XXXHI. 
Insects. 

THE  general  organization  of  insects  has  been  ex- 
plained in  Chapter  XV.,  in  the  description  of  the  may- 
bug.  The  structure  of  the  wings  and  of  the  mouth  is 
the  basis  of  the  classification  in  orders  shown  on  page 
326. 

Before  studying  some  of  the  more  important  repre- 
sentatives of  the  class  insecta  it  is  well  that  we  should 
recall  the  fact  that,  while  a  few  insects  assume  their  final 
forms  on  leaving  the  egg,  most  of  them  pass  through 
several  distinct  phases  between  the  egg  and  the  perfect 
creature. 

The  egg  gives  birth  to  a  sort  of  worm,  either  with  or 
without  legs,  and  these  creatures  are  called  larvae  ;  when 
they  have  legs  they  are  commonly  called  caterpillars. 
The  larvae  of  some  species  closely  resemble  the  perfect 
insects,  the  wings  only  being  absent,  and  these  appen- 
dages are  developed  after  the  last  casting  of  the  skin ; 
in  such  cases  the  metamorphosis  is  said  to  be  incom- 
plete. We  have  an  example  in  the  cockchafer.  In  a 
much  larger  number  of  species  the  changes  at  the  vari- 
ous stages  of  existence  are  more  remarkable,  and  it  is 
difficult  to  find  any  resemblance  between  the  larvae  and 
the  perfect  insect ;  metamorphosis  is  complete,  and  the 
butterflies  furnish  us  an  example. 

The  state  of  chrysalis,  pupa,  or  nymph,  as  it  is  vari- 
ously called,  succeeds  that  of  the  larva.  During  this 
period  most  insects  abstain  from  all  nourishment,  and 
are  apparently  dead.  To  protect  themselves  from  the 

28 


326 


A  COURSE  ON  ZOOLOGY. 


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INSECTS. 


327 


weather  and  from  their  enemies  during  this  stage, 
many  of  them  prepare  in  advance  a  silky  envelope, 
some  cover  themselves  with  clay,  others  wrap  themselves 
in  leaves,  and  still  others  hide  themselves  under  the 


FIG.  284. 


CATERPILLAR,  CHRYSALIS,  AND  IMAGO  OF  THE  GOAT-MOTH  (Cossus  ligniperda). 

bark  of  trees  or  in  the  soil.  If  a  chrysalis  be  examined 
after  short  intervals  of  time,  the  gradual  development 
of  the  organs  of  life  may  be  seen  through  the  thin  ex- 
terior envelope.  At  last,  after  an  interval  that  depends 
on  the  species  and  the  external  conditions, — sometimes 
more  than  a  year, — the  fully  developed  perfect  insect, 
or  imago,  bursts  its  prison  walls.  This  last  state  is 
ordinarily  of  short  duration:  in  most  cases  it  does 
not  last  longer  than  a  few  weeks,  in  many  it  is  limited 
to  several  days,  while  in  some  it  is  ended  in  an  hour  or 
so.  and  the  insect  dies.  The  occupation  of  the  perfect 


328 


A   COURSE   ON    ZOOLOGY. 


insects  is  limited  almost  entirely  to  the  perpetuation 
of  the  species ;  when  the  eggs  are  laid  in  places  most 
favorable  for  their  development,  the  life  of  the  insect  is 
ended. 

The  arrangement  of  the  mouth  varies  according  to 
the  diet.  Masticating  insects  (coleoptera,  orthoptera, 
etc.)  possess,  as  we  have  seen  in  the  cockchafer,  organs 
adapted  for  mastication.  In  the  hymenoptera  these  or- 


VARIOUS  FORMS  OF  CHRYSALIS. — a,  orange-tip  butterfly ;  6,  black-veined  white 
butterfly ;  c,  swallow-tailed  butterfly ;  d,  purple  emperor ;  e,  silver- washed 
fritillary  ;  /,  Duke  of  Burgundy  fritillary. 


gans  are  modified  for  sucking  or  lapping  soft  substances 
or  liquids ;  the  lower  lip  is  elongated  into  a  membranous 
tongue,  which  accompanies  the  palps,  and  the  jaws  form 
a  bivalve  sheath,  which  constitutes  the  proboscis,  In 
blood-sucking  insects  (diptera)  the  mandibles  are  modi- 
fied into  sharp  lancets,  which  are  capable  of  penetrating 


INSECTS. 


329 


the  skin  of  animals,  and  these  are  enveloped  by  a  sheath 
formed  of  the  jaws  and  the  labra. 


FIG.  287. 


MOUTH  PARTS  OF  COCKROACH  (after  Sa- 
vigny).— a,  labrum;  6,  mandibles;  c, 
first  pair  of  maxillae,  with,  d,  stipes ;  e, 
lacinia ;  /,  galea  ;  g,  maxillary  palps ; 
h,  submentum  of  second  pair  of 
maxillae  or  labium;  i,  mentum;  k, 
labial  palps;  I,  paraglossa ;  m,  lacinia ; 
the  last  two  together  forming  the 
ligula. 


MOUTH  PARTS  OF  CABBAGE  BUTTER- 
FLY (after  Leuuis).—  a,  suctorial 
tube,  formed  from  first  pair  of 
maxillae ;  6,  the  labial  palps,  be- 
longing to  the  second  pair  of 
maxillae.  At  the  base  of  the 
former,  hints  of  upper  lip,  man- 
dibles, and  second  maxillae  can 
be  seen. 


The  coleoptera  include   the   cockchafer,  stag-beetle, 
church-yard     beetle, 

Colorado    beetle,    or  FIG.  288. 

potato  -  bug,  fire-fly, 
glow  -  worm,  lady- 
bug,  meal  -  bug, 
water  -  beetle,  can- 
tharides,  and  the 
whole  beetle  order. 
The  Colorado  beetle 
is  too  well  known  by  the  damage  it  does  the  potato 
crop,  and  the  only  protection  from  it  appears  to  be  the 

28* 


COLORADO  BEETLE.— o, beetle,  natural  size;  6, 
caterpillar ;  c,  eggs.  (From  Miss  Ormerod's 
"  Injurious  Insects.") 


330 


A    COURSE   ON    ZOOLOGY. 


FIG.  289. 


sprinkling  of  the  plants  with  the  arsenical  compound 
Paris  green.  It  is  about  a  third  of  an  inch  long,  light- 
brown,  with  dark  spots.  The 
fire-fly  produces  its  brilliant  light 
by  two  spots  on  the  thorax. 
The  glow-worm  has  its  phos- 
phorescent organs  on  the  ab- 
domen, and  only  the  males  are 
winged ;  the  cause  of  the  phos- 
phorescence is  not  known. 

Among  orthoptera,  the  better 
known  are  the  grasshopper,  the 
cockroach,  the  migratory  locust, 
and  the  cricket,  Many  of  this 
order  are  jumping  insects,  and  in 
these  the  males  can  produce  a 
peculiar  rasping  sound  by  rub- 
bing the  wing-cases  against  spi- 
nous  projections  on  the  posterior 


BRAZILIAN  FIRE-FLY  (Pyro- 
phorus  noctilucus)  in  burrow 
of  mole-cricket,  showing 
the  two  oval  phosphores- 
cent organs  on  the  thorax. 


This  faculty  has  often  occasioned  confusion  of  the 
grasshoppers  with  the  common  locust.     The  migratory 


FIG.  290. 


GREEN- PACED  LOCUST  (Tragocephala  viridtfasciata). 

locust  is  a  great  destroyer  of  crops ;  sometimes  these 
insects  appear  in  vast  clouds  that  alight  and  devour 
every  green  thing  before  them,  leaving  fields  naked. 
The  cicada — common  locust — belongs  to  the  order  of 


INSECTS. 


331 


hemiptera  by  its  general  features,  but  it  lacks  the  very 
peculiarities  which  give  the  name  to  the  order  ;  its  upper 


FIG.  291. 


LOCUST  (Pachytylus  migratorius). 
FIG.  292. 


HOUSE  CRICKET  (Qryllus  domesticus). — a,  full-grown  larva ;  6,  pupa ;  c,  perfect 

insect. 

wings  are  as  delicate  and  transparent  as  the  lower 
ones.  The  female  has  at  the  extremity  of  the  abdomen 
a  borer,  which  is  used  in  piercing  the  bark  of  trees,  in 


332 


A    COURSE   ON    ZOOLOGY. 


FlG.  293. 


CICADA. 


order  to  prepare  a  place  for  the  eggs.  At  the  base  of 
the  abdomen  of  the  male  is  an  apparatus  by  which  he 
can  produce  the  monotonous  sound  so 
well  known  in  summer,  and  that 
some  species  continue  day  and  night. 
The  larvae  of  the  cicada  drop  to  the 
ground  and  bore  their  way  into  the 
soil,  remaining  a  long  number  of  years, 
sucking  the  juices  of  roots.  This 
insect  is  commonly  known  in  the 
United  States  as  the  seventeen-year 
locust. 

The  neuroptera  have  four  mem- 
branous wings,  whose  nervures  form 
a  net-work  somewhat  resembling  the 
veins  of  a  leaf.  They  are  sometimes 
made  a  suborder  of  orthoptera.  Prominent  among 
them  are  the  dragon-fly,  whose  larvae  are  aquatic  and 
very  voracious,  feeding  even  on  newly -hatched  fish ; 
there  are  a  large  number  of  species.  The  ephemera 
constitute  a  genus  of  neuroptera  whose  perfect  insect- 
life  lasts  but  a  day :  the  best  example  is  the  May-fly, 
whose  pupa  leaves  the  water  with  wings,  but  still  en- 
veloped in  a  delicate  robe,  of  which  the  insect  disen- 
cumbers itself  on  some  stem  of  grass  or  twig. 

The  coloring  matter  called  cochineal  consists  of  the 
bodies  of  a  species  of  hemiptera ;  we  will  study  the 
insect  in  the  next  chapter.  Ordinary  lice  belong  to  the 
hemiptera. 

The  hymenoptera  include  bees,  humble-bees,  wasps, 
and  ants,  We  will  defer  the  study  of  bees  until  we  con- 
sider the  useful  invertebrates.  The  humble-bees  form 
a  distinct  genus,  and  comprise  several  species,  some 


INSECTS. 


333 


making  their  nests  underground,  some  on  the  surface, 
and  others  being  borers.  They  are  all  social,  construct- 
ing nests,  gathering  wax  and  honey,  raising  the  larvae 
in  common,  and  carrying  on  in  a  less  perfect  manner 
than  the  honey-bees  the  industrious  work  for  which 
this  whole  order  is  celebrated. 


FIG.  294. 


METAMORPHOSES  OF  DRAGON-FLY  (Aeschna  grandis).—a,  larva;  b,  pupa;  c, 
perfect  insect  issuing  from  pupa  case ;  d,  perfect  insect,  with  wings  fully 
developed. 

Wasps  form  societies  sometimes  not  less  numerous 
than  those  of  the  bees.  They  also  manifest  great  in- 
dustry in  constructing  their  nests,  which  certain  species 
make  underground,  while  others  prefer  hollow  trees  or 
the  branches  of  bushes.  The  nests  are  made  of  a  sub- 
stance very  analogous  to  paper,  that  the  insects  prepare 
from  particles  of  old  wood  moistened  with  their  saliva  ; 


334 


A  COURSE  ON  ZOOLOGY. 
FIG.  295. 


METAMORPHOSES  OF  THE  MAY-FLY. 
FIG.  297. 


FIG.  296. 


LOUSE  (Pediculus 
capitis)  (magni- 
fied). 


HORNET  ( Fespa  crdbro). 


the  interior  contains  a  large  number  of  regular  cells,  in 
which  the  eggs  are  deposited.     Wasps  take  great  care 


INSECTS. 


335 


of  the  young  larvae,  feeding  them  on  the  debris  of  fruit, 
and  on  honey  which  is  but  little  inferior  to  that  of 
bees.  The  adults  live  as  foragers  in  orchards,  where 
their  depredations  often  occasion  serious  loss.  Their 
stings  are  painful,  and  sometimes  not  without  danger. 

Ants  are  social  in  their  habits,  like  the  preceding  spe- 
cies ;  there  are  several  thousand  species,  distributed  all 
over  temperate  and  tropical  countries :  the  termite,  or 
white  ant,  belongs  to  an  entirely  different  order.  They 

FIG.  298. 


A  COMMON  ANT  (Lasiusflavus).—a,  queen ;  6,  worker ;  c,  male ;  d,  larva ;  e,  pupa. 
(After  Lubbock.) 

occur,  as  we  shall  see  do  also  the  bees,  in  three  different 
forms, — males,  females,  and  workers,  and  the  latter  are 
without  wings.  The  workers  feed  the  larvae  and  take 
care  of  the  pupae,  carrying  them  into  the  sunshine,  or 
moving  them  from  place  to  place  when  danger  threatens. 
The  various  species  construct  their  nests  of  different 
materials  and  in  different  manners  ;  most  live  in  cham- 
bered galleries ;  some  simply  burrow  under  stones.  The 


•\ 


336  A  COURSE  ON  ZOOLOGY. 

giant  black  ant  prefers  a  hollow  tree  or  a  stump  ;  the 
yellow  and  brown  ants  raise  conical  ant-hills  of  sand 

or    earth    sometimes 

FIG.  299.  a    foot    high,    cham- 

bered and  traversed 
by  innumerable  gal- 
leries. Some  species 
of  ants  reduce  others 
to  slavery,  compelling 

them   to  bring  food 
PART  OF  A  GALLERY,  WITH  ANT  WORKING  ON  , 

TIPTOE,  —  Pogonomyrmex    moltfaciens,    the     and       to  nurse      the 
agricultural  ant  of  Texas.  (From  McCook.)     larvffi. 

The  lepidoptera  are 

classified  in  three  families,  different  in  their  habits  and 
their  forms ;  they  are  the  diurnal,  generally  called  but- 
terflies, the  crepuscular,  and  the  nocturnal,  the  latter 
two  being  commonly  called  moths, 

The  diurnal  lepidoptera  may  be  recognized  by  the 
erect  position  of  their  wings  when  at  rest.  They  fly 
only  during  the  day ;  their  colors  are  usually  brilliant ; 
the  chrysalis  is  usually  naked  and  attached  by  the  pos- 
terior extremity  of  its  body.  There  are  very  many 
species. 

The  crepuscular  lepidoptera  do  not  fly  all  the  evening, 
as  their  name  would  indicate ;  some  are  even  diurnal  in 
their  habits.  However,  the  wings  of  all  are  held  hori- 
zontally during  repose,  and  their  movements  produce  a 
humming  sound  when  flying.  The  chrysalis  is  usually 
enclosed  in  a  cocoon,  and  attached  to  a  tree  or  wall  or 
hidden  in  the  earth.  Some  of  the  species  are  very  large, 
one  of  the  South  American  measuring  a  foot  across  the 
extended  wings.  The  colors  are  usually  sober.  The 
nocturnal  lepidoptera  fly  only  at  night  or  at  evening 


INSECTS. 

FIG.  300. 


337 


EMPEROR  MOTH,  WITH  CATERPILLAR,  PUPA,  AND  COCOON. 
FIG.  301. 


KALLIMA  INACHIS  (from  Carus  Sterne).— a,  flying ;  6,  at  rest. 

after  sunset.     Some  of  them  have  no  proboscis,  and  a 
few  have  no  wings.     When  wings  are  present  they  are 
p       w  29 


338 


A   COURSE   ON    ZOOLOGY. 


FIG.  302. 


held  horizontally  at  rest,  or  even  folded  around  the  body. 
The  color  is  generally  dark,  and  the  chrysalis  is  enclosed 
in  a  cocoon.  This  group  is  numerous,  and  some  species 
do  much  damage,  the  larvae  eating  woollen  and  other 
fabrics. 

Mimicry,  or  imitation  of  surrounding  objects,  is  often 
exhibited  to  a  remarkable  degree  in  the  lepidoptera ;  the 
leaf-butterfly  (Fig.  301)  is  almost  indistinguishable  from 
a  brown  leaf  as  it  rests  upon  a  branch  or  twig. 

The  diptera  have  only  one  pair  of  wings,  the  missing 

pair  being  usually  replaced 
by  two  movable  append- 
ages, called  balancers.  The 
mouth  is  organized  for 
suction ;  sometimes,  as  in 
the  fly,  it  consists  of  a 
simple  fleshy  and  retractile 
proboscis,  whose  free  ex- 
tremity acts  as  a  sucker; 
sometimes,  as  in  the  mos- 
quito, there  is  a  cylindri- 
cal sheath  containing  five 

-  "— ^SE^ESf         £i  :    -j^^MMn^O^Pl 

?jHjL.  3!     scaly  darts,  each  of  which 

Ml  Bppt  111     ends  in  a  sharp  point  flat- 

1  tened  like  a  lance.  The 
metamorphosis  of  the  dip- 
tera is  generally  complete. 
The  larvae  are  usually  with- 
out limbs,  and  are  com- 
monly called  worms.  They 
are  born  and  pass  the  first 
stage  of  their  life  in  stagnant  waters  or  moist  soil  or 
among  rotten  matters.  Many  species  are  ovoviviparous. 


LIFE-HISTORY  OF  THE  GNAT  (Culex 
pipien8).—a,  larva ;  6,  pupa  ;  c,  per- 
fect insect  emerging ;  d,  male,  and 
e,  female  gnat. 


INSECTS. 


339 


FIG.  303. 


The  diptera  are  almost  as  numerous  as  the  coleop- 
tera  ;  there  a1  re  more  than  twenty  thousand  species  of 
flies,  most  of  which  are  without  special  interest,  except- 
ing that  they  frequently  become  pests. 

Mosquitoes  and  gnats  abound  in  all  parts  of  the  world, 
— as  well  in  the  frozen  regions  of  the  North  as  at  the 
equator.  They  prefer  marshy  localities,  and  sometimes 
render  such  neighbor- 
hoods almost  uninhab- 
itable. They  deposit 
their  eggs  on  the  sur- 
face of  water,  and  the 
larvae  are  aquatic. 

The  horse-fly  and 
ox-fly  are  common 
during  the  summer  in 
woods  and  pastures, 
where  they  torment 

pflttlp    tn    anoh    an   PTT       HORSE  BOT-FLY.-a,  a  horse-hair  with  eggs 

of  bot-fly ;  6,  one  egg  magnified ;  c,  larva ; 

tent  by  their  bites  as  d,  pupa ;  e,  perfect  insect,  female,  a  little 
Sometimes  to  drive  larger  than  life. 

them  nearly  mad.  The  gad-fly  or  bot-fly,  of  which  there 
are  several  species,  have  no  organs  for  perforation,  but 
deposit  their  eggs  on  the  skin  or  in  the  nostrils  of  large 
mammals,  especially  the  ox,  horse,  and  sheep.  The 
larvae  may  develop  in  the  nostrils,  or  the  eggs,  taken 
into  the  mouth  by  the  tongue  of  the  animal,  are  intro- 
duced into  the  digestive  canal,  where  they  develop,  and 
which  the  insects  leave  at  the  period  of  their  last  trans- 
formation, allowing  themselves  to  fall  on  the  ground. 


340 


A    COURSE   ON    ZOOLOGY. 


CHAPTER   XXXIV. 
Some  Useful  Invertebrates — Pisciculture. 

MANY  invertebrates  are  used  as  food ;  among  the  crus- 
tacea,  such  are  the  lobster,  crab,  and  crayfish ;  among 


MOUTH-ORGANS  OF  HONEY-BEE  (Apis  mettiftca)  (largely  magnified). — a,  tongue ; 
b,  b,  labial  palps ;  c,  c,  first  maxillae. 

mollusks,  the  oyster,  clam,  mussel,  and  scallop.  Others 
are  used  in  medicine,  such  as  the  leech  and  the  can- 
tharides.  In  studying  the  various  species,  we  have 
already  noticed  this  utility,  and  in  the  present  chapter 
we  will  consider  a  few  insects  that  have  a  considerable 


SOME    USEFUL    INVERTEBRATES. 


341 


FIG.  305. 


interest  from  an  industrial  point  of  view ;  they  are  bees, 
silk-worms,  and  cochineals. 

Bees  are  hymenoptera  in  whose  buccal  apparatus  we 
may  distinguish  an  upper  lip,  mandibles,  and  a  proboscis. 
We  will  particularly  study 
the  honey-bee,  and  we  find 
in  one  of  their  small  repub- 
lics three  classes  of  indi- 
viduals :  drones  or  males. 
females,  and  workers, —the 
last  being  sexless.  A  swarm 
or  hive  contains  one  female, 
called  the  queen,  six  or 
seven  hundred  drones,  and 
twenty  or  twenty-five  thou- 
sand workers.  The  workers 
procure  food,  construct  the 
hive,  and  take  care  of  the 
eggs,  larvae,  and  pupae ;  the 
queen  does  nothing  but  eat 
and  lay  eggs;  the  drones 
are  killed  or  driven  from 

the  hive  as  soon  as  there  are  a  sufficient  number  of 
larvae  to  insure  a  full,  new,  young  swarm.  The  females 
and  workers  have  a  sting  connected  with  a  poison-bag 
containing  formic  acid  and  other  irritating  substances ; 
this  sting  is  barbed  so  that  it  cannot  easily  be  with- 
drawn, and  its  use  as  a  weapon  is  usually  followed  by 
the  death  of  the  bee. 

Wild  bees  usually  make  their  nests  in  hollow  trees  or 
in  sheltered  cavities  in  rocks,  but  for  convenience  in 
removing  the  honey  various  forms  of  box-hives  are 
made. 

29* 


HONEY-BEE    (Apis    melliflca).  —  A, 
queen ;  B,  drone ;  C,  worker. 


342 


A   COURSE   ON   ZOOLOGY. 


The  storing  of  honey  is  done  exclusively  by  the 
workers,  and  the  organs  with  which  they  are  provided 
are  admirably  adapted  for  the  purpose.  The  posterior 
legs  are  furnished  on  the  interior  sides  with  stiff  hairs 
that  form  a  brush,  which  collects  the  pollen  of  flowers 
and  the  gummy  matters  that  cover  buds.  At  the  sides 


STING  OF  WORKER-BEE  (Apis  mellifica)  (after  Kraepelin).— a,  poison  gland ; 
6,  poison  bag ;  c,  accessory  gland ;  d,d,  outer  supporting  pieces ;  e,  inner 
sheath  enclosing  sting  proper :  A,  sting  proper ;  B,  sheath  in  which  sting 
works,  seen  from  below. 

under  the  wings  are  little  hollows  or  baskets,  in  which 
the  spoil  is  carried  home.  The  long  proboscis  penetrates 
easily  into  the  corolla  of  flowers  and  pumps  or  licks  up 
the  nectar  secreted  there.  With  these  different  materials 
the  bees  produce  honey,  wax,  and  propolis.  Honey  is 


HONEY-BEES. 


343 


nothing  but  the  nectar  of  flowers,  which  the  bees  dis- 
gorge from  their  honey-bags,  retaining  what  is  needed 
for  their  individual  food.  Propolis  is  a  resinous  and 
odorous  substance,  taken  directly  from  plants,  and  used 
for  lining  the  hive  or  stopping  up  holes  in  it,  and  oc- 
casionally for  building  a  prison  around  some  intruding 
slug.  Wax  is  secreted  by 
the  bees  themselves ;  they 
can  produce  it  when  fed  on 
honey  alone.  It  is  secreted 
by  the  walls  of  the  abdomen 


FIG.  307. 


FIG.  308. 


Hind  leg  of  honey-bee,  A ;  of  hum- 
ble-bee (Bombus  lapidarius),  B. 


FRAGMENT  OF  HONEY-COMB,  show- 
ing empty  six-sided  cells,  full 
cells  with  opening  closed,  and 
one  large  queen's  cell. 


in  the  space  between  the  segments,  and  is  used  for  the 
construction  of  the  cells  or  comb.  Each  of  these  cells 
is  a  sort  of  hexagonal  cup ;  the  comb  is  composed  of 
two  layers  of  such  cups  placed  bottom  to  bottom,  and 
in  them  are  placed  not  only  the  eggs  and  Iarva3,  but  the 
provisions  of  honey  and  pollen  necessary  for  the  life 


344  A   COURSE   ON   ZOOLOGY. 

of  the  swarm.  The  hatching  of  the  eggs  brings  forth 
larvae  that  have  no  limbs ;  these  are  cared  for  by  the 
workers  in  the  cells  in  which  they  are  born :  by  appro- 
priate care  and  nourishment  of  honey  and  pollen,  either 
queens,  drones,  or  workers  are  produced,  and  the  cells 
are  differently  shaped,  so  that  the  intended  sex  of  the 
inmate  cannot  be  mistaken.  After  a  certain  number  of 
days  these  larvae  change  into  pupae,  and  the  latter  into 
perfect  bees.  There  cannot  be  at  the  same  time  two 
queens  in  the  same  hive.  So  soon  as  a  young  queen 
prepares  to  leave  her  cell  at  the  close  of  her  metamor- 
phosis, the  old  queen  attempts  to  kill  her ;  the  workers 
prevent  this,  and  the  old  queen  leaves  the  hive,  taking 
with  her  a  part  of  the  population,  and  forming  a  new 
swarm.  The  new  queen,  who  is  left  in  the  hive,  soon 
emigrates  in  the  same  manner,  abandoning  the  hive  to 
a  still  younger  one,  and  there  may  be  in  this  manner 
four  swarms  each  season ;  the  departing  swarm  usually 
alights  on  the  branch  of  a  tree  not  far  from  the  old 
hive,  and  the  bees  allow  themselves  to  be  transferred  to 
a  new  hive  without  resistance. 

The  swarming  usually  occurs  late  in  the  spring,  and 
the  honey  is  gathered  at  the  beginning  of  summer,  so 
that  the  bees  are  able  to  renew  their  provisions  before 
winter ;  besides,  the  workers  being  away  nearly  all  day 
qn  fine  days,  the  honey  and  comb  may  be  removed 
without  sacrificing  the  bees  and  without  danger  of  being 
stung.  Sometimes  before  removing  the  honey  the  bees 
are  stupefied  with  smoke  or  with  ether  vapor ;  but 
this  is  entirely  unnecessary  where  modern  frame  hives 
are  used. 

During  the  winter,  bees  live  on  the  provisions  that  they 
have  collected  during  the  season  of  flowers.  When  too 


SILK-WORMS. 


345 


large  a  proportion  of  honey  has  been  taken  from  them, 
or  when  the  winter  is  very  long,  they  are  usually  fed  a 
mixture  of  sugar,  water,  and  honey. 

The  silk-worm  is  the  larva  or  caterpillar  of  the  mul- 
berry silk-worm,  a  species  of  lepidoptera  whose  scientific 
name  is  sericaria  mori.  It  is  a  nocturnal  moth,  having 
white  wings  with  a  few  black  rays  ;  the  body  is  velvety, 
covered  with  a  white  fur ;  the  antenna}  have  the  form 
of  foliated  palm  branches.  The  larva  is  at  first  a  little 

FIG.  309. 


MOTH  AND  EGGS  OP  THE  SILK- 
WORM (Sericaria  mori). 


SILK-WORM  (Sericaria  mori)  (about  twice  natu- 
ral size). 


black  worm  somewhat  over  a  quarter  of  an  inch  long, 
but  towards  the  end  of  its  development  it  may  attain  a 
length  of  three-quarters  of  an  inch.  Its  skin  is  almost 
without  hairs,  of  a  light  lead-gray  color  with  black  spots 
on  the  dorsal  surface.  There  are  eight  pair  of  legs.  The 
head  is  scaly  and  armed  with  jaws.  The  glands  that 
secrete  the  substance  of  silk  are  placed  in  the  interior 
of  the  body  on  each  side  of  the  median  line,  and  com- 
municate with  a  tubercle  on  the  lower  lip  by  means  of 


346  A    COURSE   ON   ZOOLOGY. 

two  very  narrow  canals.  The  silky  matter  flows  from 
the  two  glands,  assumes  the  form  of  thread  in  the 
canals,  and  dries  in  the  air  as  it  is  drawn  from  the 
minute  orifices  in  the  tubercles.  The  finest  fibres  that 
are  used  in  industry  are  formed  by  the  twisting  together 
of  three  or  four  natural  fibres.  With  these  fibres,  of 
which  some  are  white  and  some  yellow,  the  larva  rolls 
up  an  entirely  closed  oval  cocoon,  in  which  it  shuts  itself 
up  during  the  last  metamorphosis,  and  which  it  leaves  as 
a  perfect  moth,  after  having  dissolved,  by  a  peculiar 
liquid  secretion,  the  gummy  matter  that  holds  the  fibres 
together,  and  prevents  them  from  separating  from  one 
another. 

The  rearing  of  silk-worms  is  an  exceedingly  important 
industry  in  certain  countries.  It  is  conducted  in  silk- 
worm nurseries,  where  all  the  operations  are  conducted 
on  a  scientific  basis,  in  order  that  the  products  may 
have  the  greatest  superiority.  However,  the  accu- 
mulation of  enormous  quantities  of  silk-worms  in  a 
limited  space  is  accompanied  by  great  danger  of  loss 
in  case  of  epidemic  diseases  among  them,  and  the  rear- 
ing of  the  worms  must  not  be  undertaken  on  too  large 
a  scale. 

To  form  an  idea  of  the  series  of  operations  conducted 
in  an  ordinarily  large  nursery,  we  must  start  with  the 
worms  in  the  eggs.  An  ounce  of  these  contains  about 
forty-four  thousand,  and  an  ordinary  nursery  employs 
about  ten  ounces,  while  the  smaller  cultivators  cannot 
use  over  two  or  three  ounces.  In  France,  where  silk 
culture  has  reached  a  high  stage  of  development,  the 
hatching  is  undertaken  when  the  buds  of  the  mulberry 
begin  to  put  forth  little  leaves.  The  eggs  are  then  main- 
tained at  a  temperature  between  68°  and  77°,  and  the 


SILK-WORMS. 


347 


FIG.  310. 


worms  appear  in  five  or  six  days.  The  rearing  occupies 
about  a  month  ;  although  this  time  may  be  shortened 
by  keeping  the  temperature  high  and  furnishing  more 
food,  the  results  are  not  satisfactory.  During  their 
short  lives  the  worms 
cast  their  skins  several 
times — usually  four — 
and  the  time  between 
each  casting  is  called  an 
age.  At  each  age  there 
is  a  moment  when  the 
appetite  of  the  worms 
appears  insatiable.  The 
worms  hatched  from  an 
ounce  of  eggs  consume 
nearly  a  ton  of  mulberry 
leaves  before  they  reach 
maturity ;  they  then 
quit  the  nests  filled  with 
leaves  in  which  they  are 
kept,  and  crawl  on  to 
bundles  of  branches  ar- 
ranged for  them,  and 
there  begin  to  spin. 
This  work  lasts  three 
days,  after  which  the 
cocoons  may  be  de- 
tached. An  ounce  of 

eggs  produces  a  hundred  or  a  hundred  and  fifty  pounds 
of  cocoons. 

When  the  cocoons  have  been  collected,  the  best  speci- 
mens are  set  aside  for  future  rearings,  and  from  these 
the  moths  are  liberated  in  two  or  three  weeks;  they 


SILK-SECRETING  APPARATUS.— A,  organs 
that  secrete  the  silky  matter  in  the  silk- 
worm :  a,  posterior  part  of  the  head ; 
6,  canals  for  the  exit  of  the  silky  matter ; 
c,  reservoir  and  silk  gland ;  B,  nipple 
on  the  lower  lip  from  the  tip  of  which 
the  silk-fibre  issues. 


348 


A  COURSE  ON  ZOOLOGY. 


produce  other  eggs,  which  are  preserved  until  the  follow- 
ing season.  Twenty  ounces  of  cocoons  yield  about  an 
ounce  of  eggs.  The  cocoons  from  which  silk  is  to  be 
made  are  exposed  to  steam ;  the  pupa  are  thus  killed, 
and  the  silk  is  unrolled  and  reeled. 

The  sericaria  mori,  or  bombyx  mori,  which  produces 
the  best  silk,  can  be  reared  only  where  the  mulberry 
flourishes,  but  there  are  other  silk-producing  worms, 
species  of  bombyx,  that  feed  on  oak-leaves,  rice-leaves, 
and  on  the  leaves  of  poplar,  elm,  white  thorn,  and  cas- 
tor-oil bean. 

The  cochineal  insects  are  species  of  hemiptera  in  which 
FIG.  311. 


COCHINEAL  (Coccus  cacti).— a,  living  on  cactus  (Opuntia) ;  b,  male ;  c,  female. 

the  female  lives  flattened  out  on  the  leaves  of  certain 
plants ;  as  soon  as  the  eggs  are  laid  she  swells  up  and 


PISCICULTURE.  349 

dies,  protecting  the  eggs  with  her  dried  body.  The 
ordinary  cochineal  lives  in  Mexico,  on  the  leaves  of  a 
cactus  called  nopal,  and  is  largely  cultivated.  Little 
nests  containing  the  females  ready  to  lay  eggs  are  sus- 
pended on  the  spines  of  the  nopal,  and  the  larvae  soon 
appear  on  the  leaves  and  spread  over  the  plant.  The 
males  have  wings,  but  the  females  are  apterous,  and 
remain  on  the  plant,  from  which  they  are  collected, 
killed  by  heat,  and  dried  in  the  sun.  They  contain  the 
coloring  matter  called  carmine. 

Lac,  which  is  ordinarily  known  as  shell-lac,  is  a  resin 
produced  on  certain  varieties  of  fig-trees  in  Asia  by  a 
species  of  hemiptera,  called  the  coccus  lacca. 

PISCICULTURE. 

Since  we  have  from  time  to  time  spoken  of  useful 
animals,  we  should  not  pass  in  silence  the  efforts  that 
have  been  made  to  preserve  certain  species  and  to  enable 
them  to  multiply.  Fish,  in  particular,  are  important 
from  an  alimentary  point  of  view  ;  the  entire  population 
of  certain  towns  consists  of  fishermen,  and  it  is  not  as- 
tonishing that  the  art  of  breeding  and  protecting  fish, 
called  pisciculture,  has  been  practised  from  very  remote 
epochs.  It  was  known  to  the  Chinese  and  to  the 
ancients,  has  long  been  carried  on  in  Europe,  and  is 
now  successfully  conducted  on  a  large  scale  in  the 
United  States.  There  is  no  difficulty  in  understanding 
the  interest  that  attaches  to  the  preservation  in  our 
lakes  and  watercourses  of  useful  species,  such  as  the 
carp,  perch,  bass,  trout,  and  salmon.  Artificial  hatcher- 
ies have  been  invented,  and  the  habits  of  the  fish  have 
been  closely  studied;  for,  in  order  to  ascertain  the  best 
conditions  for  reproduction,  we  must  know  how  and  in 

30 


350 


A    COURSE   ON    ZOOLOGY. 


what  surroundings 
the  eggs  are  laid, 
and  what  nourish- 
ment must  be  fur- 
nished the  young 
fish  or  spawn. 

Some  species, 
such  as  the  trout 
and  salmon,  de- 
posit their  eggs  in 
little  cavities  in 
sand  or  gravel,  or 
in  the  interstices 
of  rocks;  others, 
£  such  as  the  perch. 
g  carp,  and  roach, 
^  attach  the  eggs  to 
|  aquatic  plants  or 
*  stones  by  the  aid 
of  a  viscid,  glue- 
like  matter.  These 
conditions  being 
known,  it  is  easy 
to  establish  an  ar- 
tificial hatchery. 
For  the  perch 
tribe  a  frame  of 
wood,  supporting 
a  net  -  work  of 
branches  and  a- 
quatic  plants,  may 
be  sunk  in  the 
water  by  means  of 


PISCICULTURE.  351 

stones ;  while  for  the  salmon  species  a  bed  of  gravel  in 
running  water  would  be  required. 

Remy,  a  poor  French  fisherman,  was  the  first  to  in- 
troduce artificial  hatching  into  Europe,  being  led  to  his 
invention  by  observing  the  immense  destruction  of  the 
eggs  and  young  by  various  enemies  in  nature.  He 
simply  enclosed  the  eggs,  mixed  with  the  milt,  in  zinc 
boxes  perforated  with  holes,  which  were  then  sunk  in 
the  river  until  the  eggs  were  hatched.  At  present  a 
number  of  shallow  troughs  are  usually  employed,  ar- 
ranged side  by  side,  and  at  gradually-increasing  ele- 
vations; water  flows  through  the  whole  series;  this 
arrangement  permits  the  hatching  of  eggs  of  different 
dates  to  be  conducted  simultaneously,  and  the  separation 
of  spawn  of  different  ages. 

When  the  eggs  are  hatched,  the  spawn  must  be  care- 
fully fed,  the  food,  of  course,  depending  on  the  species ; 
young  trout  and  salmon  thrive  well  on  the  larvae  of 
insects  and  on  smaller  fish. 

Pisciculture  consists  not  only  in  supplying  streams 
and  lakes  with  eggs  and  young  fish  under  the  most 
favorable  conditions;  it  includes  also  the  precautions 
which  must  be  observed  to  fully  populate  large  rivers. 
At  certain  seasons  of  the  year  various  fish  ascend  the 
rivers  for  spawning,  and  everything  that  may  pre- 
vent or  interfere  with  their  free  running  up  and  down 
must  be  carefully  avoided.  Dams  in  rivers  are  effective 
barriers  to  the  running,  and  laws  usually  require  that 
fish-ways  or  fish-ladders  shall  be  provided  by  which  the 
fish  may  ascend,  jumping,  as  they  easily  do,  from  one 
step  to  the  next. 

Among  the  fish  that  run  up  the  rivers  we  may  mention 
shad,  salmon,  sea-trout,  sturgeons,  and  eels.  During 


352  A    COURSE    ON    ZOOLOGY. 

the  months  of  March  and  April  millions  of  young  eels, 
hardly  larger  than  threads,  ascend  the  rivers  in  compact 
masses;  under  suitable  conditions  these  grow  rapidly, 
and  in  a  few  years  will  weigh  as  many  pounds.  Towards 
autumn  the  young  fish  have  grown  large  enough  to  take 
care  of  themselves,  and  they  go  down  to  the  sea. 

In  conclusion,  pisciculture  consists  in  the  care  given 
to  the  breeding  of  fish.  "  If  fish  be  hatched  in  the 
hope  of  increasing  them,  the  method  of  the  agricultu- 
rist must  be  followed;  he  sows  his  grain  in  the  most 
favorable  ground,  and  especially  in  a  soil  carefully  pre- 
pared for  the  seed  ;  to  place  young  fish  in  a  lifeless  river 
is  like  planting  wheat  in  chalk  or  in  sand"  (Blanchard). 


CHAPTER  XXXV. 
Obnoxious  Invertebrates. 

WHILE   studying  worms  we  came  across   a   certain 
number  of  parasites.     Besides  these  there  are  among 

the  invertebrates,  and 
especially  among  insects 
and  arachnides,  a  large 
number  of  species  inju- 
rious because  of  their 
parasitic  habits. 

We  have  already  men- 
tioned the  cattle-flies  and 
the  bot-flies;  there  are 
certain  species  that  at- 
tack man.  One  of  these 
is  a  Mexican  fly,  of  which  the  female  deposits  her  eggs 


OBNOXIOUS    INVERTEBRATES.  353 

in  the  nostrils  of  those  who  sleep  out ;    these  eggs  pro- 
FIG.  314. 


METAMORPHOSES  OF  COMMON  FLEA  (Pulex  irritaw)  (magnified).— a,  larva ;  6, 
pupa  or  nymph :  c,  perfect  insect. 


FIG.  315. 


FIG.  316. 


MOUTH  APPARATUS  OF  THE  FLEA.— The  BEDBUG  (Cimex  lecttUaria), 

long  serrated  mandibles  are  on  each  magnified, 

side  of  a  median  needle  which  rep- 
resents the  labrum.  Exterior  to  these 
mandibles,  two  grooved  joints  rep- 
resent the  lower  lip.  The  maxillary 
palps  are  still  further  out. 

duce  carnivorous  larvae  that  penetrate  profoundly,  and 
occasion  terrible  suffering  and  frequently  death. 
x  30* 


354  A   COURSE   ON    ZOOLOGY. 

Fleas  are  apterous  (wingless)  insects,  organized  for 
jumping,  and  having  a  mouth  armed  with  small  lancets 
that  are  modified  mandibles  ;  these  lancets  are  enclosed 
in  a  sheath  formed  by  the  union  of  the  jaws.  The  bite 
is  painful  because  the  insect  secretes  an  irritating  saliva. 

The  bedbug  is  a  hemiptera,  and  is  still  more  objec- 
tionable than  the  flea.  It  has  one  pair  of  rudimentary 
wings,  and  when  it  is  at  rest  the  short  beak  is  hidden  in 
a  fold  of  the  abdomen.  The  mandibles  and  the  jaws 
are  modified  into  bearded  needles,  enclosed  in  a  sheath 
formed  by  the  upper  and  lower  lips. 

Among  the  parasitic  arachnides  may  be  classed  the 

acarids   or  mites,  crea- 

FIG.  317.  '.       .  , 

tures  having  a  discoid 

or  globular  body,  and 
a  mouth  ordinarily 
adapted  for  sucking. 
Among  these  are  the 
ticks,  which  attach 
themselves  firmly  to  the 
skin  of  mammals  by 

a,  TromUdium  holosericeum,  female  (mag-  nf     n      qprT.flfprj 

nifled  9  diameters) ;  6,  larva,  full  grown    means     Ot      a      serrate' 
(harvest-bug).  mouth   formed   by  the 

union  of  the  jaws. 

The  harvest-bug  or  harvest-tick  is  the  larva  of  an 
acarid  called  trombidium.  It  has  six  feet,  like  the  larvai 
of  most  acarids,  and  is-  found  in  the  woods  and  fields 
in  July  and  August.  It  often  occasions  great  incon- 
venience to  men,  its  presence  in  the  skin  producing 
violent  itching. 

The  itch-insect,  or  sarcoptes  scabiei,  is  hardly  visible  to 
the  naked  eye  ;  the  female  lives  in  the  skin  of  man  and 
of  various  animals,  such  as  the  ox,  sheep,  dog,  etc.,  and 


OBNOXIOUS    INVERTEBRATES. 


355 


burrows  out  galleries,  where  it  feeds  on  the  juices  se- 
creted because  of  the  irritation  it  occasions.  These 
burrows  appear  on  the  surface  of  the  skin  like  the 
sinuous  scratches  of  a  pin  ;  the  larvae  crawl  out  of  them 
and  hide  themselves  under  a  neighboring  epidermic 
pellicle. 


FIG.  318. 


ITCH-INSECTS.— A,  male ;  B,  female ;  pi,  p2,  p3,  p4,  the  four  pair  of  feet ;  6, 
mouth ;  a.  anus. 

SOME  INSECTS  INJURIOUS  TO  AGRICULTURE  AND  TO  INDUSTRY. 

Coleoptera. — We  have  already  spoken  of  the  ravages 
committed  by  beetles  of  various  kinds  and  in  their 
various  forms.  Both  the  larvae  and  the  perfect  insect 
are  exceedingly  destructive.  There  are  about  a  hundred 
species  of  beetle  that  live  at  the  expense  of  the  pine- 
tree  ;  different  species  attack  different  kinds  of  tree, 
some  eating  leaves,  others  preferring  twigs,  while  some 


356  A   COURSE   ON   ZOOLOGY. 

bore  into  the  wood.  The  rose  beetle,  the  asparagus 
beetle,  sugar-cane  beetle,  and  carpet  beetle — the  latter 
being  exceedingly  destructive  to  woollens  of  all  kinds — 
are  only  too  well  known. 

Of  the  dermiptera,  the  earwigs  destroy  fruits  and 
flowers. 

Orthoptera.— The  cockroaches  eat  and  soil  our  food; 
grasshoppers  and  locusts  devour  roots  and  young  sprouts. 

Hemiptera. — Plant  lice  live  socially  on  most  plants ; 
they  cause  a  more  or  less  rapid  destruction  by  absorbing 
all  the  nutritive  juices.  The  phylloxera,  so  fatal  to  the 
grape-vine,  is  closely  related  to  the  plant  lice.  The  har- 
lequin cabbage-bug  and  tree-hoppers  are  hemiptera. 

Neuroptera.— The  termites,  which  will  presently  be  de- 
scribed, are  particularly  injurious  to  wooden  construc- 
tions. 

Hymenoptera, — The  damage  caused  by  ants  and  wasps 
has  already  received  notice.  Certain  of  these  insects  are 
very  injurious  to  trees. 

Lepidoptera.  —  In  the  state  of  larva  or  caterpillar 
nearly  all  this  order  are  destructive  to  certain  vege- 
table or  animal  matters.  We  may  cite  all  the  varieties 
of  silk-worm,  the  cabbage-worm,  larch-lappet,  hemlock- 
worm,  corn-worm,  and  the  peach-  and  apple-twig  moths. 

We  will  terminate  with  a  few  details  concerning  some 
species  whose  history  is  of  particular  interest. 

Grasshoppers  have  very  long  hind  legs  and  a  powerful 
masticating  apparatus.  But  they  are  not  nearly  as 
much  dreaded  as  their  near  relatives,  the  migratory  lo- 
custs. At  certain  epochs  innumerable  legions  of  these 
insects  start  from  desert  regions  of  the  Rocky  Mountains, 
of  Arabia  and  Tartary.  and  rise  high  in  the  atmosphere, 
until  they  encounter  winds  that  carry  them  great  dis- 


OBNOXIOUS  INVERTEBRATES.  357 

tances.  The  light  of  the  sun  is  darkened  as  they  pass, 
and  the  air  is  filled  with  a  dull  sound,  caused  by  the 
striking  of  their  wings.  At  last,  carried  by  the  wind, 
they  fall  like  a  rain-storm  ;  trees  are  stripped  of  leaves, 
and  the  branches  break  under  the  weight  of  the  insects ; 
all  vegetable  life  disappears ;  harvests  are  devoured. 
Then,  to  complete  the  desolation,  the  bodies  of  the  in- 
sects that  are  crushed  in  the  mass,  exhausted  by  hunger 
or  by  fatigue,  form  on  the  naked  ground  a  thick  layer 
of  decomposing  matter  that  serves  as  a  hot-bed  of  dis- 
ease. Eussia,  Poland,  and  Hungary  have  been  several 
times  plague-stricken  from  this  cause. 

The  phylloxera  lives  as  a  parasite  on  the  roots  of  the 
grape-vine,  and  increases  with  frightful  rapidity.  It  is 
rendered  still  more  destructive  by  the  fact  that,  be- 
sides the  apterous  individuals  that  remain  fixed  on  the 
roots,  there  is  a  winged  form  that  carries  the  pest  in  all 
directions.  The  winged  insect  lives  on  the  leaves,  and 
lays  eggs  that  produce  apterous  individuals.  The  latter 
penetrate  under  the  skin  of  the  root,  and  by  their  suck- 
ing apparatus  kill  the  vine  by  pumping  all  the  juices  of 
the  plant. 

During  the  warm  season  the  apterous  individuals 
produce,  by  a  sort  of  budding,  large  numbers  of  young, 
among  which  some  develop  into  winged  insects.  The 
latter  migrate,  and,  as  we  have  seen,  lay  eggs,  from 
which  wingless  and  less  injurious  individuals  are  hatched, 
but  from  these  are  produced  the  destructive  and  the 
winged  forms. 

The  termites,  or  white  ants,  are  of  many  species ;  they 
have  multiplied  to  such  an  extent  in  certain  towns  of 
France  that  attempts  to  destroy  them  have  proved 
almost  useless.  At  La  Bochelle  they  invaded  the  public 


358  A    COURSE    ON    ZOOLOGY. 

buildings,  destroyed  all  woodwork,  and  devoured  the 
archives.  The  damage  wrought  by  the  termites  is  much 
greater  by  the  fact  that  it  is  never  apparent  from  the 
exterior.  Indeed,  the  creatures  dread  the  light,  and  are 
very  careful  to  leave  absolutely  intact  the  surface  of  the 
wood  they  are  destroying  ;  joists  and  supports,  appar- 
ently perfect,  thus  give  way 
when  the  interior  is  galleried 
in  all  directions. 

The  clothing  and  carpet 
moths  are  injurious  only  in  the 
state  of  larvae.  They  are  then 
veritable  plagues  for  all  mat- 
ters composed  of  wool,  feathers, 

HOUSE-MOTH.  ,     .       ,  '  .    ' 

hair,  horn,  tortoise-shell,  skm, 

and  for  collections  of  natural  history. 

Generally  they  seek  dark,  quiet  places  and  uniform 
temperature,  so  that  the  best  way  to  prevent  their  rav- 
ages is  to  shake  frequently  and  expose  to  bright  light 
and  sudden  changes  of  temperature  all  articles  that 
might  be  subjected  to  their  attacks.  It  is  sometimes 
quite  difficult  to  recognize  the  presence  of  these  crea- 
tures, even  by  close  examination;  for  sometimes  the 
larvae  make  a  covered  gallery,  leaving  the  outside  fibres 
in  position  ;  sometimes  the  sheath  or  cocoon  which  it 
makes  for  itself  is  covered  with  the  debris  of  the  mate- 
rial on  which  it  rests,  and  the  colors  are  so  arranged  that 
no  difference  is  detected  on  first  inspection. 

Most  of  these  house-moths  belong  to  the  family  called 
tineidse,  each  species  of  which  prefers  fabrics  of  special 
material,  but,  unfortunately,  many  of  them  seem  able  to 
adapt  themselves  to  whatever  matter  of  animal  origin 
they  can  get. 


GLOSSARY. 


Acanthoceph'ala  (pi.)  ("  thorny- 
heads"),  a  small  group,  or  phylum, 
of  worm-like  organisms,  living 
within  the  bodies  of  other  ani- 
mals; they  have  hooks,  or  spines, 
upon  the  head. 

Acar'ida  (pi.)  ("atoms,"  "indivis- 
ibles"), mites;  insects  of  low 
type. 

Aceph'ala  ("headless"),  an  order  of 
mollusks,  to  which  the  oyster  and 
clam  belong. 

Actinozo'a  (pi.)  ("  rayed  animals"),  a 
class  of  marine  animals,  including 
corals,  etc. 

JEpyor'nis  ("tall  bird"),  a  huge  ex- 
tinct bird  of  Madagascar. 

JEstiva'tion  ("  summering"),  the  tor- 
pid state  of  certain  animals  in  the 
hottest  season. 

Albi'nism,  abnormal  whiteness  in  the 
skin,  hair,  or  feathers. 

Amblyp'oda  (pi.)  ("  clumsy-footed"),  a 
group  of  huge  extinct  mammals 
that  probably  had  some  of  the 
characters  of  the  elephant. 

Amoe'ba  ("  changing"),  a  minute  ani- 
mal organism  capable  of  changing 
its  form  at  will. 

Amphib'ia  (pi.)  ("  double  living"),  an 
order  of  vertebrate  animals,  living 
at  first  in  the  water,  and  later  capa- 
ble of  living  in  either  air  or  water, 
as  frogs,  newts,  etc. 

Amphip'oda  (pi.)  ("  having  feet  in 
either  direction"),  an  order  of  crus- 
taceans which  have  feet  partly 


directed  forwards  and  partly  back- 
wards. 

Anat'omy  ("  cutting  up"),  the  science 
of  organic  structure. 

Anten'na  ("a  sail-yard"),  a  horn-like 
process  on  the  head  of  certain  insects 
and  crustaceous  animals ;  a  feeler. 

A'phid.    See  APHIS. 

A'phis  ("  unsparing"  or  "profuse"),  a 
genus  of  minute  insects  called 
plant-lice  ;  they  are  exceedingly 
destructive  to  vegetation. 

Appendicula'ta  (pi.)  ("  appendaged"), 
a  great  phylum,  including  the  Ro- 
tifera,  Chaetopoda,  and  Arthropoda. 

Ap'tera  (pi.)  ("  no  wings"),  a  class  of 
wingless  insects. 

Arach'nida  (pi.)  ("  spiders"),  a  group 
of  articulate  animals,  including 
spiders,  scorpions,  and  mites. 

Arthrop'oda  (pi.)  ( "jointed  feet").  See 
ARTICULATA.  A  division  of  the 
animal  kingdom  nearly  equivalent 
to  Articulata.  But  the  term  Arthrop- 
oda is  the  wider  in  its  significa- 
tion, and  is  now  more  often  em- 
ployed than  Articulata. 

Articula'ta  (pi.)  ("jointed"),  a  di- 
vision of  the  animal  kingdom,  in- 
cluding animals  whose  bodies  are 
composed  of  joints  or  rings.  See 
ARTHROPODA. 

Artiodac'tyla  (pi.)  ("even-toed"),  a 
suborder  of  ungulate  animals  hav- 
ing an  even  number  of  toes  on  each 
foot,  as  swine,  camels,  and  rumi- 
nants. 

359 


360 


GLOSSARY. 


Aacid'ianB  ("pouched"),  a  class  of 
tunicates  showing  marked  verte- 
brate characters. 

A'ves  ("  birds"),  a  class  of  oviparous 
vertebrates  having  feathers  and 
warm  blood  ;  the  birds. 

Avifau'na  ("bird  fauna"),  the  birds 
of  a  region  collectively. 

Batra'chia  (pi.)  ("frogs").  See  AM- 
PHIBIA. 

Biol'ogy  ("discourse  on  life"),  the 
science  of  life  and  living  things. 

Brachiop'odaC'  arm-footed"),  an  order 
of  headless  bivalve  molluscoids 
having  two  fleshy  spiral  arms. 

Branchiop'oda  (pi.)  ("gill-footed"),  a 
division  of  crustaceans  having  gills 
upon  the  feet. 

Bryozo'a  (pi.)  ("  moss-animals").  The 
same  as  POLYZOA. 

Bunodon'ta  (pi.)  ("  mound- toothed"), 
a  group  of  artiodactyl  mammals, 
so  called  from  the  tubercles  on  the 
crowns  of  the  molar  teeth.  Here  be- 
long the  pig  and  the  hippopotamus. 

Carina'tse  (pi.)  ("  keeled"),  an  order 
of  birds  having  the  breast-bone 
provided  with  a  keel.  By  far  the 
largest  number  of  existing  species 
of  birds  belong  to  this  order. 

Cen'tipedes  ("  hundred -footed"),  a 
group  of  myriapodous  animals. 

Cephalop'od*,  ("  head-footed"),  a  class 
of  molluscs  having  a  circle  of  ten- 
tacles around  the  mouth,  as  the 
cuttle-fish  and  squid. 

Ceta'cea  ("  a  sea-animal"),  an  order 
of  mammals  living  in  the  sea,  as 
dolphins  and  whales. 

Chsetop'oda  ("  bristle-footed"),  a  group 
of  worms,  including  earth-worms. 

Chilog'natha  (pi.)  ("  lip-jawed"),  a 
group,  or  order,  of  Myriapoda  hav- 
ing the  two  lower  jaws  united  to 
form  a  lip. 

Chirop'tera  (pi.)  ("  hand-winged"),  an 
order  of  mammals  having  the  fore 
limbs  adapted  for  flight ;  the  bats. 


Cirripe'dia  ("curl-footed"),  a  group 
of  crustaceans  having  a  number 
of  long  curled  processes  like  feet; 
barnacles. 

Coelentera'ta  (pi.)  ("  hollow  entrails"), 
a  large  group,  or  phylum,  of  radi- 
ated animals,  including  the  Actin- 
ozoa,  Hydrozoa,  and  Ctenophora. 

Cce'lom,  or  Coelo'ma  ("  hollow"),  the 
body-cavity  ;  the  cavity  within  the 
animal  body. 

Coelo'mata  (pi.)  ("  hollows"),  properly, 
the  plural  of  CCELOMA  ;  used  also  as 
the  designation  of  those  animals 
which  have  a  creloma,  including 
vertebrates  and  many  of  the  inferior 
animals. 

Coleop'tera  (pi.)  ("sheath-winged"), 
an  order  of  insects  with  two  pairs 
of  wings,  the  outer  serving  as  a 
sheath  or  covering,  like  the  beetle. 

Collem'bola  (pi.)  ("  tail-leapers"),  the 
spring-tails,  or  snow-fleas;  a  small 
group  of  insect-like  creatures  gen- 
erally classed  as  insects  of  a  low 
type. 

Copep'oda  (pi.)  ("oar-footed"),  an 
order  of  crustaceans  with  oar-like 
feet.  Many  of  the  low  organisms 
called  fish-lice  belong  here. 

Crania'ta  ("having  a  skull"),  those 
vertebrates  that  have  a  brain  en- 
closed in  a  bony  or  cartilaginous 
case  or  skull. 

Crusta'cea  (pi.)  ("  having  a  crust  or 
shell"),  a  class  of  articulated«ani- 
mals  having  a  shelly  coating,  like 
the  lobster  and  crab. 

Ctenoph'ora  (pi. )  ("  comb-bearing"),  an 
order  of  Coelenterata,  comprising 
many  small  gelatinous,  pellucid, 
marine  forms,  characterized  by 
comb-shaped  swimming  organs. 

Decap'oda  (pi.)  ("ten-footed"),  the 
highest  order  of  living  crustaceans, 
including  the  crabs,  lobsters,  and 
prawns. 

Dimor'phism    ("double    form"),   the 


GLOSSARY. 


361 


property  possessed  by  certain  low 
animals  of  producing  different 
forms  of  offspring. 

Dinor'nis  ("  terrible  bird"),  an  extinct 
genus  of  birds  found  in  New  Zea- 
land. 

Dip'noi  (pi.)  ("  double  breathing"),  a 
small  class  of  fish-like  animals  (by 
many  regarded  as  fishes  of  a  prim- 
itive type)  which  have  lungs  as 
well  as  gills. 

Dip'tera  (pi.)  ("  double-wing"),  an 
order  of  insects  which  have  two 
wings  only,  as  the  house-fly, 

Echinoder'mata  (pi.)  ("  hedgehog- 
skinned"),  a  class  of  sea-animals 
which  have  a  covering  of  tough 
skin. 

Edenta'ta  (pi )  ("  deprived  of  teeth"), 
an  order  of  mammals  having  no 
front  teeth,  as  the  sloth  and  ant- 
eater. 

Entozo'a  (pi.)  ("  within  animals"), 
animals  which  live  within  the 
bodies  of  other  animals. 

Fau'na  ("  goddess,  or  nymph,  of  cat- 
tle"), the  various  kinds  of  animals 
found  in  a  country. 

Foraminif'era  (pi.)  ("having  an  open- 
ing"), an  order  of  minute  animals 
having  shells  the  chambers  of 
which  communicate  by  means  of 
small  perforations. 

Galli'nse  (pi.)  ("hens"),  an  order  of 
birds  represented  by  the  domestic 
fowl.  • 

Gan'oids  ("splendid  appearance"), 
fishes  distinguished  by  the  angular 
form  of  their  bony,  enamelled 
scales. 

Gasterop'oda  ("  belly-footed"),  an 
order  of  mollusks  having  under 
the  belly  a  fleshy  disk  which  serves 
instead  of  feet,  as  the  snail. 

Gastrot'richa  (pi.)  ("  hairy-bellied"),  a 
small  phylum  of  worm-like  ani- 
mals, having  cilia  on  the  ventral 
surface. 


Gemma'tion  ("  budding"),  a  process 
of  reproduction  by  which  a  part  of 
the  parent  is  detached  to  form  the 
offspring. 

Gephyr'ea  (pi.)  ("  bridge-like"),  a  class 
of  worm-like  Podaxonia,  by  some 
writers  regarded  as  true  worms,  but 
according  to  a  later  view  placed 
near  the  Polyzoa. 

Hemip'tera  (pi.)  ("  half  a  wing"),  an 
order  of  insects  whose  wings  are 
partly  membranous  and  partly  like 
those  of  a  beetle. 

Histol'ogy  ("  discourse  on  webs  or 
tissues"),  the  minute  anatomy  of 
the  tissues. 

Hy'brid  ("an  outrage"),  the  offspring 
of  parents  which  belong  to  different 
species. 

Hydrozo'a  ("water-animals"),  a  di- 
vision of  the  animal  kingdom  con- 
taining aquatic  animal  organisms 
of  a  low  order  of  development,  in- 
cluding jelly-fishes. 

Hymenop'tera  (pi.)  ("  membrane- 
winged"),  an  order  of  insects  hav- 
ing four  membranous  wings,  as 
wasps  and  bees. 

Hyracoi'dea  (pi.)  ("hyrax-like  ani- 
mals"), a  suborder  or  group  of  sub- 
ungulate  mammals,  including  the 
hyrax  (coney,  or  daman),  the  klip- 
das,  and  a  few  other  remarkable 
forms. 

Ichthyol'ogy  ("  discourse  about  fish"), 
the  branch  of  natural  history  treat- 
ing of  fishes. 

Infuso'ria  ("  decoction  -  animals"), 
microscopic  animalcules  (protozoa) 
found  in  water,  and  especially  in 
infusions  of  plants,  etc. 

Insectiv'ora  (pi.)  ("  insect-eaters"), 
an  order  of  small  mammals,  such 
as  the  mole,  shrew,  and  true 
hedgehog,  living  chiefly  upon  in- 


I 
31 


Isop'oda    (pi.)    ("equal-footed"),    an 
order  of  crustaceans  having  the 


362 


GLOSSARY. 


legs  alike  in  size  and  position  ;  it 
includes  the  sow-bugs,  etc. 

Lar'va  ("  a  mask"),  an  insect  in  a 
caterpillar  state;  an  undeveloped 
animal. 

Lepidop'tera  (pi.)  ("  scale-winged"), 
the  order  of  insects  which  consists 
of  butterflies,  moths,  etc. 

Mammalia  (pi.)  ("  pertaining  to  the 
breast"),  the  class  of  animals  that 
suckle  their  young. 

Marsupia'lia  (pi.)  ("pouched"),  an 
order  of  mammals  the  female  of 
which  carries  her  young  in  a  pouch, 
as  the  kangaroo  and  opossum. 

Maxilla  ("  a  jawbone"),  the  jaw  in 
animals  and  insects. 

Metamor'phosis  ("  change  Across"),  a 
change  of  form. 

Mollus'ca  (pi.)  ("  soft"),  a  division  of 
animals  having  soft  bodies  and  no 
internal  skeleton,  as  snails. 

Mollus'coids  ("  mollusk-like"),  ani- 
mals (like  polyzoa,  brachiopods, 
and  tunicates)  that  somewhat  re- 
semble mollusks. 

Monotrem'ata  ("  one  vent"),  an  order 
of  mammals  that  lay  eggs. 

Morphol'ogy-C'  a  discourse  on  form"), 
the  department  of  science  treating 
of  the  organs  and  structure  of 
.  animals. 

Myriop'oda  (pi.)  ("  ten  -  thousand- 
footed"),  a  class  of  articulate  ani- 
mals having  many-jointed  feet. 

Nematoi'dea  ("thread-like"),  a  group 
or  class  of  slender  worm-like  ani- 
mals; thread-worms. 

Neurop'tera  (pi.)  ("  nerve-winged"), 
an  order  of  insects  having  trans- 
parent nerved  wings,  as  the  dragon- 
fly. 

Nidifica'tion  ("making  a  nest"),  the 
act  of  building  nests. 

O'cydrome  ("swift  runner"),  a  rare 
bird  of  New  Zealand,  that  cannot 
fly,  but  runs  very  swiftly ;  there  are 
several  species. 


Ornithol'ogy  ("  discourse  on  birds"), 
that  part  of  zoology  which  treats 
of  birds. 

Orthop'tera  (pi.)  ("  straight-winged"), 
that  order  of  insects  which  in- 
cludes grasshoppers,  etc. 

O'vum  (pi.  O'va),  the  egg. 

Par'asite  ("  a  guest"),  an  animal  that 
lives  upon  or  within  another  ani- 
mal. 

Perissodac'tyla  (pi.)  ("odd-toed"),  a 
suborder  of  ungulate  mammals 
having  an  odd  number  of  toes,  as 
the  tapir,  rhinoceros,  and  horse. 

Phyllop'oda  (pi.)  ("leaf-footed"),  an 
order  of  branchiopod  crustaceans 
having  flattened  feet,  like  the 
brine-shrimps. 

Phylloxe'ra  ("  leaf-drier"),  a  genus  of 
aphids,  or  plant-lice,  one  species 
of  which  (P.  vastatrix,  the  "  devas- 
tating phylloxera")  is  exceedingly 
destructive  to  the  grape-vine  in 
certain  regions. 

Phylum  ("  a  tribe"),  any  sub-king- 
dom or  primary  division  of  the 
animal  kingdom,  such  as  the  verte- 
brata. 

Pinnipe'dia  (pi.)  ("fin-footed"),  a 
suborder  of  carnivorous  mammals, 
including  the  seals  and  walrus. 

Pis'ces  (pi.)  ("  fishes"),  that  class  of 
the  vertebrata  which  includes  the 
fishes. 

Plana'rians  ("  flat"),  a  group  of  flat- 
tened fresh-water  worms.  • 

Platyhel'mia  (pi.)  ("  flat- worms"),  an 
extensive  phylum,  including  tape- 
worms, leeches,  and  many  other 
worm-like  forms. 

Podaxo'nia  (pi.)  ("  axis  -  footed"),  a 
phylum  of  animals,  including  the 
Gephyrea  and  the  Polyzoa. 

Pol'yps  ("  many-footed  "),~  animals 
having  no  organs  of  locomotion, 
and  provided  with  a  circle  of  ten- 
tacles round  the  mouth. 

Polyzo'a    (pi.)   ("many  animals"),  a 


GLOSSARY. 


363 


class  of  low  polyp-like  animals 
that  form  colonies,  or  compound 
animals  composed  of  a  great  num- 
ber of  individuals. 

Porif  era  ("  pore-bearing"),  a  class  of 
protozoan  animals,  including  the 
sponges. 

Prima'tes  (pi.)  (" first"  or  "highest"), 
an  order  of  mammals,  including 
the  most  highly  developed  species, 
such  as  the  lemurs,  apes,  and  man. 

Proboscid'ea  (pi.)  ("  having  a  trunk"), 
a  group  of  subungulate  mammals 
having  a  long  prehensile  nose 
(trunk  or  proboscis),  as  the  ele- 
phant. 

Protozo'a  (pi.)  ("  first  animals"),  the 
name  of  the  lowest  forms  of  animal 
life. 

Pter'opods  ("  wing-footed"),  an  order 
of  mollusks  that  have  wing  like 
expansions  of  the  foot,  which  serve 
as  swimming  organs. 

Pu'pa,  the  third  stage  of  existence  of 
an  insect. 

Quadru'mana  (pi.)  ("  four-handed"), 
four-handed  mammals,  as  apes. 

Quad'rupjed  ("four-footed"),  an  ani- 
mal having  four  feet. 

Radia'ta  (pi.)  ("  rayed"),  marine  ani- 
mals whose  structure  is  radiate. 
The  term  is  now  used  as  a  descrip- 
tive one,  and  many  authorities  do 
not  recognize  it  as  the  name  of  any 
group  of  animals. 

Radiola'ria  (pi.)  ("  small-rayed"),  a 
class  of  minute  oceanic  protozoa 
having  flinty  skeletons.  In  some 
places  there  are  large  masses  of 
rock  made  up  mainly  of  the  flinty 
remains  of  fossil  Radiolaria. 

Rati'tse  (pi.)  ("  raft-like"),  an  order  of 
birds  which  have  no  keel  upon  the 
breast-bone,  including  the  ostrich, 
rhea,  apteryx,  cassowary,  emeu, 
and  several  extinct  birds,  many  of 
them  very  large. 

Reptil'ia  (pi.)  ("  crawlers"),  the  class 


of  vertebrata  that  includes  croco- 
diles, lizards,  frogs,  and  snakes. 

Reticula'ria  (pi.)  ("netted"),  nearly 
the  same  as  Foraminifera. 

Rhizop'oda*(pl.)  ("  root -footed"),  a 
class  of  protozoans  of  very  low  and 
primitive  type,  so  named  from  the 
root-like  processes  by  which  some 
of  the  species  are  attached,  or  by 
which  they  move  about. 

Roden'tia  (pi.)  ("  gnawing  animals"), 
an  order  of  mammals  with  chisel- 
shaped  incisors  (front  teeth)  adapt- 
ed for  gnawing,  as  rabbits,  rats, 
mice,  squirrels,  gophers,  beavers, 
porcupines. 

Rotifera  (pi.)  ("wheel-bearers"),  a 
class  of  animalcules  with  disk-like 
bodies. 

Sau'ria  (pi.)  ("lizards"),  a  group  of 
reptiles  that  includes  lizards,  croco- 
diles, etc. 

Sire'nia  ("  sea  -  nymphs,"  "mer- 
maids"), an  order  of  herbivorous 
marine  mammals,  .including  the 
dugong,  the  manatee,  and  the  ex- 
tinct stellerine. 

Stomap'oda  (pi.)  ("  mouth-footed  "),  an 
order  of  crustaceans  "having  the 
feet  placed  around  or  near  the 
mouth. 

Subunsula'ta  (pi.)  ("  slightly  hoofed"), 
a  group  of  mammals  usually  placed 
among  the  Ungulata,  but  not  hav- 
ing complete  hoofs,  including  the 
hyrax,  elephant,  etc.,  most  of  the 
species  being  extinct. 

Tax'idermy  (" arrangementof  skins"), 
the  art  of  preparing,  stuffing,  and 
mounting  the  skins  of  animals  and 
birds. 

Taxon'omy  ("  law  of  arrangement"), 
the  classification  of  organisms; 
the  systematic  and  natural  ar- 
rangement of  animals  and 
plants. 

Teleos'teans  (pi.)  ("  completely 
i  boned" ),  a  subclass  of  fishes  having 


364 


GLOSSARY. 


a  complete  bony  skeleton  ;  true  or 
typical  fishes. 

Tere'do  ("borer"),  one  of  the  so-called 
ship-worms  or  wood-worms.  The 
teredo  is  a  mollusk  thafcbores  holes 
in  wooden  ships,  and  in  piles  and 
other  timbers  placed  in  the  sea- 
water. 

Ter'mites  (pi.)  ("wood-worms"),  a 
group  or  family  of  insects  known 
as  white  ants;  but  they  are  not 
true  ants.  Their  destructive  rav- 
ages are  noticed  in  the  body  of  this 
work. 

Thysanu'ra  (pi.)  ("tassel-tails"),  a 
group  of  low  insect-like  forms,  gen- 
erally considered  as  insects  of  a  low 
type.  The  so-called  "silver-fish," 
common  in  kitchens  and  closets,  is 
a  well-known  example. 

Tin'amou,  a  South  American  bird  of 
several  species,  generally  classed  as 
one  of  the  Carinatse,  and  as  related 
to  the  domestic  fowl.  But  it  has 
many  of  the  structural  features  of 
the  ostrich-like  birds,  or  Ratitae, 
which  it  also  resembles  in  its 
habits. 

Tragruli'na  (pi.)  ("goat-like"),  a  group 
of  small  tropical  artiodactyl  mam- 
mals resembling  deer,  but  not  very 
closely  related  to  them  nor  to  any 


true  ruminant,  including  the  chev- 
rotains,  or  deerlets. 

Tunica'ta  (pi.)  ("wearing  a  tunic"), 
a  class  of  molluscoids  (by  some 
classed  as  vertebrates)  which  are 
protected  by  a  leather-like  covering 
instead  of  a  shell. 

Tylop'oda  (pi.)  ("pad-footed"),  a 
group  of  artiodactyl  mammals 
having  pads  under  the  soles  of  the 
feet ;  the  camel,  llama,  and  alpaca 
are  examples. 

TJngula'ta  (pi.)  ("hoofed  animals"). 
an  order  or  group  of  mammals 
provided  with  hoofs  or  strong  nails 
on  the  toes,  including  the  horse, 
ox,  deer,  elephant,  etc. 

Ver'mes  (pi.)  ("worms"),  the  name 
given  to  the  class  of  worms;  but 
the  class  is  not  a  well-defined  one, 
and  is  to  be  regarded  as  made  up 
of  several  distinct  groups. 

Vertebra'ta  (pi.),  the  division  of  ani- 
mals which  have  vertebrae  and  a 
bony  skeleton. 

Zobl'ogy  ("  discourse  on  animals"), 
the  science  of  animals. 

Zo'ophyte  ("  plant-animal"),  any  ani- 
mal that  is  fixed  in  its  place  by  a 
stem  and  in  other  respects  re- 
sembles a  plant.  The  name  is  not 
much  used  at  present  by  zoologists. 


INDEX. 


Acephalans,  170. 

Albatross,  273. 
Albumen,  18. 
Alligators,  307. 
Annelides,  154. 
Anseres,  277. 
Ant-eaters,  233. 
Antelopes,  243. 
Ants,  335. 
Aorta,  28. 
Arachnida,  130. 
Armadillos,  232. 
Arteries,  20. 
Articulates,  126. 

Badger,  208. 
Batrachians,  125,  309. 
Bears,  211. 
Beaver,  224. 
Bedbug,  354. 
Bees,  332,  341. 
Beetle,  138. 
Birds,  124,  268. 
Blood,  18. 
Boars,  250. 
Bones,  68. 
Bot-fly,  339. 
Buffaloes,  242. 
Buzzards,  285. 

Cachalot,  260. 
Caecum,  36. 
Camelidse,  246. 
Capillary  system,  21. 
Capybara,  228. 
Carinatae,  268. 
Carnivora,  204. 
Carp,  114-317. 


Catfish,  317. 
Cattle,  240. 
Cell,  9. 

Cephalopods,  165. 
Cerebellum,  45. 
Cervidse,  236. 
Cetacea,  259. 
Chamois,  244. 
Chelonia,  299. 
Chickadees,  294. 
Chicken,  94,  281. 
Chinchilla,  228. 
Civet,  218. 
Coccyges,  288. 
Cochineal,  348. 
Cockatoos,  288. 
Cockroach,  330. 
Codfishes,  315. 
Colon,  36. 

Colorado  beetle,  329. 
Columbse,  283. 
Condor.  287. 
Coots,  280. 
Cormorants,  276. 
Cranes,  280. 
Cray-fish,  131. 
Creepers,  293. 
Crocodiles,  307. 
Crows,  296. 
Crustaceans,  130. 
Cyclostomata,  324. 

Deer,  236. 
Diaphragm,  16. 
Digestion,  29. 
Diptera,  338. 
Dog,  87. 
Dolphin,  259. 


365 


366 


INDEX. 


Dormouse,  226. 
Ducks,  277. 
Dugongs,  263. 
Duodenum,  36. 

Eagles,  284. 
Echidna,  268. 
Edentata,  231. 
Eels,  319. 
Elephants,  252. 
Elk,  239.  , 
Equidae,  254. 
Ermine,  206. 
Expiration,  17. 

Falcons,  285. 
Feathers,  94. 
Ferret,  206. 
Fishes,  125-310. 
Flamingo,  278. 
Flea,  354. 

Foraminifera,  183. 
Fox,  213. 
Frog,  108. 

Gall-bladder,  37. 
Gallinse,  280. 
Ganoids,  323. 
Gasteropods,  167. 
Giraffidse,  246. 
Glands,  33. 
Gnu,  245. 
Goatsucker,  291. 
Goose,  277. 
Grouse,  283. 
Guinea-fowl,  282. 
Guinea-pigs,  230. 
Gulls,  273. 

Haemoglobin,  19. 
Hair,  56. 
Hares,  230. 
Hearing,  60. 
Heart,  23. 
Hedgehog,  203. 
Hen-hawk,  285. 
Herodiones,  278. 
Heron,  279. 


Herring,  318. 
Hippopotamus,  249. 
Hogs,  251. 
Horse-fly,  339. 
Horses,  254. 
Humming-birds,  291. 
Hyenas,  219. 

Ibis,  279. 

Ichneumon,  218. 

Infusoria,  157-181. 

Insalivation,  39. 

Insectivora,  130,  201. 

Insects  injurious  to  agriculture,  etc., 

355. 

Inspiration,  16. 
Intestine,  35. 
Itch-insect,  354. 

Jackals,  214. 
Jaguar,  215. 
Jays,  296. 
Jejunum,  36. 

Kangaroos,  264. 
Kingbird,  292. 
Kingfishers,  288 
Kites,  285. 

Lamprey,  324. 
Larks,  295. 
Larynx,  14. 
Lemmings,  227. 
Leopards,  215. 
Limicolse,  280. 
Lions,  215. 
Liver,  37. 
Lizards;  105,  301. 
Locomotion,  68,  77. 
Locusts,  330. 
Longipennse,  273. 
Loons,  273. 
Lungs,  13. 
Lynxes,  217. 

Mackerel,  312. 
Macrochires.  291 
Mammals,  124. 


INDEX. 


367 


Mammals,  orders  of,  188. 
classification  of,  190. 
Man,  7, 189. 
Manatees,  263 
Marmots,  224. 
Marsupials,  264. 
Martens,  206. 
Mesentery,  36." 
Mexican-fly,  362. 
Mocking-bird,  292. 
Mollusks,  162. 
Monkeys,  195. 
Monotremata,  267. 
Moose,  239. 
Muscles,  78. 
Musk-rat,  228. 
Myriapods,  131. 
Mystacoceti,  261. 

Nematoidea,  161. 
Nerves,  47. 
Newts,  309. 
Night-hawks,  291. 
Nightingale,  292. 

Odontoceti,  259. 
Odontoglossse,  278. 
(Esophagus,  34. 
Ophidia,  304. 
Opossum,  265. 
Organs  of  sense,  53. 
Ornithorhynchus,  267. 
Osprey,  285. 
Ostriches,  270. 
Otters,  205. 
Owls,  287. 

Palate,  34. 
Paludicolse,  280. 
Pancreas,  38. 
Panda,  210. 
Pangolins,  232. 
Panther,  215. 
Parasites,  158. 
Parrots,  288. 
Partridge,  283. 
Passeres,  292. 
Pelicans,  276. 


-  Penguins,  272. 
Pericardium,  23. 
Perissodactyla,  253. 
Peritoneum,  36. 
Petrel,  273. 
Pharynx,  34. 
Pheasants,  282. 
Phylloxera,  357. 
Pici,  289. 
Pickerel,  317. 
Pigeons,  283. 
Pisciculture,  349. 
Plasma,  18. 
Pleura,  14. 
Plovers.  280. 
Polecat,  206. 
Porcupine,  229. 
Porpoise,  259. 
Prairie-dogs,  224. 
Prairie-hen,  283. 
Proboscidia,  252 
Psittaci,  288. 
Pulmonary  veins,  26. 
Puma,  216. 
Pygopodes,  272. 

Quagga,  259. 
Quail,  283. 

Rabbits,  231. 
Raccoon,  210 
Races,  191. 
Radiates,  172. 
Raptores,  284. 
Ratitse,  268. 
Rats,  225. 
Rectum,  36. 
Reindeer,  238. 
Reptiles,  124,  299. 
Rhinoceros,  259. 
Ribs.  73. 
Rbdentia,  221. 
Rotatoria,  157. 
Ruminants,  234. 

Sable,  208. 
Salamanders,  309. 
Salmon,  317. 
31* 


368 


INDEX. 


Sarcode,  183. 
Sardines,  318. 
Seals,  219. 
Selachoids,  321. 
Serpents,  304. 
Shad,  319. 
Sharks,  321. 
Sheep,  242. 
Shrew,  203, 
Sight,  63. 
Silkworm,  345. 
Sirenia,  263. 
Skeleton,  7,  68,  72, 
Skunk,  208. 
Sloth,  231. 
Smell,  58. 
Snipes,  280. 
Sparrows,  294. 
Spider,  146. 
Spinal  cord,  48. 
Spleen,  37. 
Squirrels,  223. 
Stomach,  34. 
Storks,  279. 
Sucker,  317. 
Suina,  249. 

Tapir,  259. 
Taste,  58. 
Teeth,  31. 
Terns,  273. 
Terrapin,  300. 
Thrush.  292. 
Tiger,  215. 
Tissue,  10. 


Tortoises,  299. 
Trachea,  14. 
Trematoidea,  161. 
Trichinosis,  161. 
Tritons,  309. 
Trout,  317. 
Tubinares,  273 
Turkey,  281. 
Turtles,  300. 

Ungulata,  238. 

Venous  system,  21. 
Ventricles,  24. 
Vertebrae,  73. 
Vertebrates,  123. 
Vocal  apparatus,  84. 
Voice,  84. 
Vultures,  285. 

Walrus,  220. 
Wasps,  333. 
Weasels,  207. 
Whales,  261. 
Whippoorwills,  291. 
Wild-cat,  218. 
Wolf,  212. 
Wolverene,  207.    - 
Woodcocks,  280. 
Woodpeckers,  289 
Worms,  154. 
Wrens,  294. 

Zebra,  258. 


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